QUICK RELEASE CLAMP: Easily mount on the seatpost or remove the rear rack, you can change the seat height easily. Comes with tools and installation instructions. Suitable for most bikes like MTB, road bike (your seatpost diameter should be less than 32MM) but not suitable for rear suspension bike. LARGE LOAD: This bike rack is made of aluminum alloy which is durable, strong and well constructed to hold a lot of weight. W-SHAPED AND ADJUSTABLE DESIGN: The design with W-shaped bars to prevent the bag from hitting the tires, keeps your bag safe. FENDER: FENDER provides more protection for your bag or panniers in rain or muddy road, keep your bike dryer and cleaner.You can also remove this rear fender when you don’t need it. NOTE: Not suitable for suspension bike, fat tire bike, women’s cruiser bike, bicycle seat, etc. The included nuts are lock nuts. When you installed the nut, the rubber at the inside of the nut will prevent you from tightening. Just use a tool to tighten the nut.