The FK Surf bike mount surfboard rack is made of a sturdy aluminium frame with anti-rust capabilities. Easy to attach and detach with push button quick release arms. The FK bike rack has padded arms and securing straps for ultimate board protection when in use. Fits all bikes with round seat posts of 25MM and 32MM. Adjustable arms for all surfboard sizes. Easy under seat attachment. Push button quick release arms. Fits all bikes with 25MM to 32MM round seat posts. Adjustable arms for different board sizes. Padded arms for maximum surfboard protection. Easy to detach arms when not in use. Sturdy aluminium frames Anti-rust.