Mucky Nutz Butt Fender. Protect your prized posterior from Soggy Arse Syndrome. Lightweight, discreet and very effective, it keeps your backside clean, comfortable, and happy.. Available in black for subtle style or reflective for safety-conscious riders.. Made in the UK from 100% recycled plastic.. 1 year warranty. Technical Shizzle. • Works well with all bikes with tyres up to 3" wide. • Fits most standard double-rail saddles.