【Size】Inner roller is 4 inch wide, the inner diameter of mounting hole is about 1.3 cm or 0.5 inch. Fits 4 inch wide center roller bracket. Overall width is about 18 cm or 7.09 inch 【Material】The boat trailer bow roller is made of nylon material, which is sturdy and wear resistant. It is lightweight yet has a strong load bearing capacity, making it reliable for long term use 【Smooth & Noiseless Rolling】The boat trailer roller ensures the boat runs smoothly on the trailer and helps cushion and protect your boat and yacht trailer accessories 【Easy to Install】The boat trailer roller is easy to install and use, allowing you to tow your boat more efficiently while saving energy and time 【Wide Application】This boat trailer bow roller marine boat tug roller is widely used for transporting large cargo in factories, docks, ports, warehouses, and other production areas. Suitable for boats, trailers, ships, and yachts Specification: Material: Nylon Size Chart: Inner Roller Width: 4 inch Total Width: 18 cm or 7.09 inch Inner Mounting Hole Diameter: about 1.3 cm or 0.5 inch Package Includes: 1 Piece Boat Trailer Roller Note: Please allow slight variations due to manual measurement and differences in display monitors