King Pin for Semi Trailer Reviews: 5 Best Options

When you own a semi trailer or fifth wheel, protecting your investment starts with the right king pin. Whether you need a heavy-duty lock to prevent theft or a weldable replacement pin for your bolster plate, choosing the right component ensures safety and peace of mind.

This guide reviews five top options, from anti-theft locks with warning tags to forged steel pins built for strength. Each product is evaluated on its unique features to help you find the perfect fit for your rig.

BOYISEN 5th Wheel King Pin Lock – Convenient Handle

The BOYISEN king pin lock stands out with its integrated handle, which turns the cylinder outward instead of downward for easier locking and unlocking. Made from solid steel rather than casting steel, it resists weather and breakage. You get three keys, and each lock uses a unique blossom lock mechanism, so you don’t have to worry about another BOYISEN owner having the same key.

For added peace of mind, 2025 batch locks include a key ID printed on the key, making replacements simple if you lose yours. The heavy-duty construction and thoughtful design make this a reliable choice for securing your fifth wheel or semi trailer. It’s a practical upgrade that combines strength with user-friendly features.

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• More Convenient with Handle, Compared with other kingpin lock, BOYISEN trailer kingpin Lock add handle and turn cylinder outward instead of downward, more convenient while lock or unlock for 5th wheel
• Keyed Unique, no worry about another BOYISEN kingpin lock owner will have the same key. BOYISEN anti theft trailer lock using blossom lock, not easy to break; Come with 3 keys for your lock, so you can keep one as backup
• Heavy Duty Construction: This 5th wheel hitch lock is made of solid steel instead of casting steel, strong enough for weather resistant, hard to break. The heavy duty steel will add more difficulties for steal drills, and lasts for years
• Key Lost? No Worrying! In 2025 batches locks, there's a key ID printed on the key, please note it down or take a photo of it, provide us with the key ID to copy the key if your keys are lost
• High Visibility: This Kingpin lock is designed with a warning tag, so you could notice if it is still stay in place, and remind you of removing it when you want to hitching
• Universal Fit: ideal for trucking companies, RV dealers or fleet drivers, used for RVs, Boats and Campers Semi-Truck

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RVMATE 5th Wheel Lock – Heavy Duty Security

The RVMATE king pin lock is built from heavy-duty steel copper with welded construction and an electrostatic coating for weather resistance. Its bright yellow warning tag provides a strong visual deterrent, reminding you to remove it before hitching. With a height of 83 mm and an internal diameter of 74 mm, it fits universal 50 mm trailer pins.

This lock is designed to prevent thieves from connecting to your kingpin, avoiding unauthorized movement. The durable body and eye-catching yellow tone make it easy to spot, reducing the risk of driving away with the lock still attached. If you want a straightforward, robust security solution for your RV or semi trailer, this model delivers reliable protection.

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• [Keep Your 5th Wheel Secure] : King pin lock can prevent thieves from connecting your fifth wheel kingpin and avoid unauthorized movement. The durable construction, eye-catching yellow lock and tag serve as a warning and deterrent against theft to keep your 5th wheel secure.
• [Dimension]: The dimension of the trailer king pin lock is 83 mm in height, with an internal diameter of 74mm, a universal fit for 50 mm diameter trailer pins. Thus, the lock can be widely applied in semi trailers, 5th wheels, trucks, boats, containers and many other scenarios.
• [High Quality Material]: Trailer king pin is made of heavy duty steel copper, processed with welding construction. The surface adopts electrostatic treatment, featuring the body with weather resistance and anti-rust, making it sturdy enough and hard to break even by experienced thieves. Therefore effectively increase the safety factor and reduce the probability of theft when installed onto trailer.
• [Warning Tag]: The main tone of bright yellow designed as a sign of strong visible warning. The chain with fluorescent warning tag hanging down passes on message to someone to try and steal : Caution! King pin lock installed! If a would-be thief sees the lock, they'll likely move on to an easier target.
• [Easy to Use]: The trailer hitch lock is rather easy to use. You just need to engage the lock onto the trailer hitch, then insert the key into lock cylinder and rotate 180 degrees, the king pin lock firmly installed. (Attention: Every lock has its own keys. Different locks don't share the keys.)

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METOWARE 5th Wheel King Pin Lock – Precision Anti-Theft

The METOWARE king pin lock features high-strength iron with a double-layer electrostatic coating for weather resistance and durability. It includes a 12-inch chain and a bright red warning label tag that reminds you to remove it before hitching. The precision anti-theft design encloses the main pin lock to help prevent drilling attacks.

Installation takes seconds, and the lock comes with two keys so you have a spare. The unique design makes locking and unlocking straightforward, while the red tag adds an extra layer of safety. If you’re looking for a lock that combines strength with a thoughtful anti-theft approach, this model offers solid protection for your fifth wheel or semi trailer.

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• EYE-CATCHING WARNING LABELS:This 5th wheel King Pin lock comes with a 12-inch chain and bright red warning label tag attachment that will remind you to remove it before hitching. Each warning label has a warning message in English to keep you safe.
• HIGH STRENGTH MATERIAL:This king pin lock is made of high-strength iron for durability, weather resistance and resistance to damage. This lock is coated with a double layer of electrophoretic paint to prevent corrosion and rust for a more reliable performance, it is perfect for protecting your trailer on the road or hauling.
• UNIQUE DESIGN:The Kingpin lock is easy to lock and unlock, takes seconds to install and comes with two keys so you don't have to worry about losing them.
• PRECISION ANTI-THEFT DESIGN:This fifth wheel king pin lock can well enclose the main pin lock to effectively prevent drills, saws and other damaging tools. The heavy-duty precision mechanism protects your trailer perfectly so you don't have to worry about it.
• UNIVERSALITY:The 5th wheel king pin lock is the best choice for RVs, boats, and camping semi-trailers, the petite size can be applied to a wide range of vehicles, adding convenience to your journey.

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Buyers Products KP20050 Forged Trailer King Pin – Weldable Strength

The Buyers Products KP20050 is a 2-inch SAE king pin designed for weldable installation on your bolster plate. It maintains a hardness of 302-363 BHN, ensuring strength and reliability for your fifth wheel setup. This forged pin is built to handle heavy loads and tough conditions, making it a solid replacement or upgrade part.

Buyers Products is known for engineering components that perform under pressure, and this king pin is no exception. Whether you’re repairing a worn pin or building a new trailer, this weldable option provides the durability you need. It’s a straightforward, no-fuss solution for those who prefer a permanent, high-strength connection.

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• 2" SAE king pin
• Maintains hardness of 302-363 BHN
• More Than Just Parts: From snow and ice equipment to toolboxes, hydraulics, towing, truck and trailer hardware to our innovative lighting products-it's amazing what Buyers Products can do for your truck
• We Do Things The Right Way: We design products like we're building them for ourselves, because we are; Our teams are staffed with engineers and experts who know how to make a product exceptional
• Durable and Dependable: Founded in 1946, Buyers Products has become a leader in the truck equipment industry though our commitment to customer care, innovation, and value across our range of products

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AMPLock U-PLS Strong King Pin Lock – Industrial Security

The AMPLock Strong-series king pin lock is engineered with a custom-molded fit for fifth wheel trailers, semi trailers, and commercial rigs. Its precision design helps prevent traction-based theft using chains or cables. Manufactured in North America from ductile cast iron with stainless steel removable parts, it resists corrosion and wear.

The push-to-lock system allows quick installation without fumbling with keys—just push to lock. This lock is keyed alike for commercial fleets, so one key works for multiple locks. If you need industrial-grade security that’s easy to use, this model combines robust materials with a smooth locking mechanism for enhanced protection.

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• HEAVY-DUTY KING PIN LOCK FOR TRAILERS & RVs – This Strong-series king pin lock secures 5th wheel trailers, semi trailers, and commercial rigs with a custom-molded fit designed to eliminate wobble and prevent unauthorized towing. Built from ductile cast iron and stainless steel for superior strength, it reinforces travel trailer accessories, semi truck accessories, and trailer security while offering reliable protection for equipment stored or parked long-term.
• PRECISION DESIGN WITH INDUSTRIAL SECURITY – Featuring AMPLock’s engineered structure, this king pin lock for semi trailer setups helps prevent traction-based theft using chains or modified towing systems. Its advanced disc lock includes a rotating drill-resistant face and millions of unique combinations, making lock picking extremely difficult. Ideal for king pin locks for 5th wheel, RV trailer locks, and fifth wheel king pin lock applications within automotive towing.
• DURABLE MATERIALS WITH STAINLESS COMPONENTS – Manufactured in North America using ductile cast iron for the body and stainless steel for removable parts, this trailer pin lock resists corrosion, harsh weather, drilling attempts, and mechanical force. Whether protecting a semi trailer lock, securing a fifth wheel camper, or reinforcing commercial hauling equipment, its smooth and durable construction provides dependable year-round performance for fifth wheel in demanding conditions.
• EASY PUSH-TO-LOCK INSTALLATION FOR QUICK SECURITY – AMPLock’s smooth push-to-lock system allows instant installation without tools, making it one of the easiest upgrades for 5th wheel hitch lock users, trailer king pin lock systems, and hitch pin lock setups. The molded fit ensures a precise, stable connection with zero looseness, offering effortless day-to-day operation for RV owners, fleet managers, and trailer operators who also use trailer hitch pin locks across multiple setups.
• ANTI-THEFT DESIGN WITH KEYED-ALIKE OPTION – Designed for strong resistance against cutting, drilling, torches, and impact, this king pin lock enhances trailer security through industrial-grade engineering. The keyed-alike option lets users operate multiple locks with a single key, simplifying security management while maintaining high protection. Ideal for securing travel trailers, RVs, semi trailer king pins, and commercial equipment.

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Buyer’s Guide: What to Consider

When choosing a king pin for your semi trailer, focus on material, fit, and security features. Here are key factors to consider.

• Material Strength: Look for solid steel, forged steel, or ductile cast iron for durability and resistance to cutting or weather damage.
• Locking Mechanism: Choose between handle-operated, push-to-lock, or key-only designs based on your preference for ease of use.
• Fit and Compatibility: Ensure the lock fits your king pin diameter—most are designed for 50 mm (2-inch) pins, but always verify.
• Warning Features: Bright tags or chains remind you to remove the lock before hitching, preventing accidents and damage.
• Key Security: Consider unique keying, keyed alike for fleets, or key ID systems for easy replacement if keys are lost.

Conclusion

Selecting the right king pin or lock depends on your specific needs. For ease of use, the BOYISEN with its handle is a great choice. If you need a weldable replacement, the Buyers Products forged pin offers reliable strength.

For anti-theft, the AMPLock provides industrial security, while the RVMATE and METOWARE offer solid deterrents with warning tags. Consider your trailer type and usage to find the best fit.