CURT’s 5/8” zinc-plated hitch pins deliver exactly what Montana contractors need — reliable security for ball mounts and receiver accessories. Four distinct models handle everything from basic 2x2 receiver tubes to heavy-duty 3x3 applications, with the zinc finish providing practical corrosion resistance that makes sense for inland use.
Skip the stainless if you’re not towing near saltwater. The zinc version gives you reliable rust resistance — perfect for Montana’s freeze-thaw cycles and road salt exposure without the marine-grade coating you don’t need.
Four Models for Different Jobs
The standard #21500 weighs just 0.550 lbs and fits any 2” x 2” receiver with its 0.625” diameter shaft. Basic, bulletproof, gets the job done. But CURT got smart with their variants.
The #21505 adds a grooved tip that lets you attach the retainer clip from any angle — 360-degree access means no more fumbling around trying to line up clip holes when you’re underneath a truck in the snow. At 0.600 lbs, the weight penalty is negligible.
For cold-weather work, the #21510 wraps the handle in rubber while keeping the standard hole design. Same 0.600 lb weight as the grooved version. That rubber grip matters when you’re pulling pins with frozen fingers or wet gloves.
The heavy-duty #21506 steps up to 3” x 3” receivers with the same grooved tip design and a 21,000 lb GTW rating. That’s serious capacity for equipment haulers running bigger trailers.
Built for Real-World Abuse
Every pin uses high-strength solid steel construction with a clear zinc-plated finish for rust and corrosion resistance. The 105-degree bent handle creates a useful finger grip that works even with heavy gloves.
The zinc coating handles Montana conditions better than raw steel but doesn’t pretend to be marine-grade. Black powder coat offers a stealthier look and high corrosion resistance for those who want aesthetics, while stainless steel provides the highest rust protection for marine environments. But for most Montana contractors pulling equipment trailers between job sites, zinc delivers solid protection for the conditions you’ll actually face.
All pins include spring-steel retainer clips — the basic insurance that keeps your expensive equipment attached to your truck. CURT’s safety warning is simple: never exceed the lowest weight capacity of any component in your towing system.
| Specification | Standard Pins (#21500, #21505, #21510) | Heavy-Duty (#21506) |
|---|---|---|
| Diameter | 5/8” (0.625”) | 5/8” (0.625”) |
| Receiver Size | 2” x 2” | 3” x 3” |
| Weight | 0.550-0.600 lbs | Not specified |
| Rated Capacity | Not specified | 21,000 lbs GTW |
Installation and Compatibility
Installation follows the standard process: slide your ball mount or accessory into the receiver tube, insert the pin through the aligned holes, then secure with the retainer clip. Grooved variants let you slide the clip into the groove from any direction.
Standard pins (#21500, #21505, #21510) fit any 2” x 2” receiver tube with a standard 5/8” pin hole. The heavy-duty #21506 requires a 3” x 3” receiver. That 5/8” diameter is industry standard — these pins work with any properly sized receiver from any manufacturer.
CURT backs these pins with a limited lifetime warranty — one year on the finish, one year on parts. Each model is tested and rated to specific weight capacities, with the #21506 certified for 21,000 lbs GTW.
Frequently Asked Questions
Q: What’s the real advantage of the grooved tip models?
The grooved tip on #21505 and #21506 allows 360-degree clip access — you can attach the retainer clip from any angle instead of having to rotate the pin to line up holes. Saves time and frustration, especially when working in tight spaces or bad weather.
Q: Is the zinc coating durable enough for year-round Montana use?
The clear zinc plating provides rust and corrosion resistance suitable for inland conditions. It handles road salt and weather exposure well. It provides reliable rust resistance for general use.
Q: Why choose the rubber-handled #21510 over standard models?
The rubber-coated handle provides enhanced comfort and secure engagement, particularly valuable when operating with cold, wet, or gloved hands. The grip makes pin removal easier in adverse conditions common on Montana job sites.
Q: What’s included with each pin?
Each pin comes with one 5/8” zinc-plated hitch pin and one spring-steel retainer clip. That’s everything needed for secure installation.
Q: Can I use the standard 2” pins in a 3” receiver with an adapter?
While adapters exist, match your pin to your receiver size for maximum safety. The #21506 is specifically designed for 3” x 3” receivers and rated for 21,000 lbs GTW — use it when running heavy-duty applications.
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