"PRODUCT DETAILS Nylon Rolling Cantilever Slide Gate Rollers for Round 4"" OD Post & 2-3/8"" OD Gate Frames. Malleable Steel Gate Roller Body (Assembly) manufactured for long life and to prevent rust. Cantilevered, Sliding, Rolling Gate Rollers, Roll Smoothly and Securely for Years of Service. Cantilevered Gate Roller Assembly has Adjustable U Shaped Bolts Designed for Easy/Sturdy Attachment. Gate Wheels are made of Nylon for Long Reliable Gate Hardware Life & smooth rolling operation."