Wonwopn 4 Inch Boat Trailer Roller Assembly, 4 inch pvc roller assembly, PVC bow bell for 4-inch bracket, corrosion-resistant

Wonwopn 4 Inch Boat Trailer Roller Assembly is a PVC bow bell roller kit sized for 4-inch brackets that protects your boat hull and eases loading and launching.

This roller assembly combines a non-marring PVC roller, end bells, and a 1/2-inch attachment bolt into a compact unit engineered for boat trailers with 4-inch bracket mounts. Built to resist corrosion and road wear, the assembly cushions hull contact, centers the bow, and reduces shock transmitted during towing and retrieval. The design and dimensions make it a straightforward replacement or upgrade for common trailer bow-stop setups.

What are the exact dimensions and hardware included?

The full assembly measures about 7-1/4 inches long with an outer bell diameter near 5-1/4 inches. The inner rolling section is approximately 3.92 inches long with a 3.5-inch diameter, and the supplied attachment bolt is 1/2 inch thick. These proportions are intended to suit standard 4-inch trailer brackets and give proper clearance from trailer components.

• Overall length: 7-1/4 inches
• Outer bell diameter: ~5-1/4 inches
• Inner roller: 3.92 inches long × 3.5 inches diameter
• Attachment bolt: 1/2-inch diameter

How does the PVC material benefit my boat and trailer?

The roller is molded from PVC, which resists corrosion and does not rust like metal components. PVC is also non-marring so it reduces scuffs and scratches on gelcoat or painted hulls while remaining durable under repeated use. Compared with softer rubbers, PVC keeps its shape and provides reliable support for bow loads.

• Non-marring surface protects hull finish
• Corrosion-resistant — suitable for fresh and saltwater use
• Durable shape retention under load and road shock

How does this assembly improve launching, loading, and towing?

The bow bell profile centers the vessel on the bow stand, guiding it on and off the trailer during retrieval and launch. End bells prevent direct hull contact with bolts or brackets and absorb impact, which reduces pounding transmitted to the hull. The roller section supports bow weight and smooths movement during loading on ramps.

• Centers bow for repeatable, smooth alignment
• End bells protect hull from hardware contact
• Roller cushions road shock during towing and ramp loading

Will this fit my trailer and how do I install it?

It is designed to fit 4-inch bracket mounts commonly used for bow stops on many trailers; check bracket inner width and bolt diameter to confirm fit. Installation typically involves removing the old unit, sliding the assembly into the bracket, and securing it with the 1/2-inch bolt. Use appropriate washers and secure torque per trailer manufacturer guidance.

• Check bracket size and bolt clearance before purchase
• Simple bolt-on installation — replace like-for-like
• Use proper fasteners and torque values for secure mounting

Who is this for: The Wonwopn 4 Inch Boat Trailer Roller Assembly suits boat owners, trailer shops, and DIYers who need a corrosion-resistant, non-marring bow roller that fits 4-inch brackets. It is ideal for freshwater and saltwater trailers where long-lasting PVC construction and straightforward bolt-on replacement are priorities. If you want to protect gelcoat, improve centering during launches, and reduce hull contact with trailer hardware, this assembly is an economical and practical option.