Velcro straps attach to saddle rails and seat post. Has a water resistant zipper and reflective tail light loop for any weather conditions. Main compartment features neoprene pockets for organizing tire repair and money. Easily accessible, external multi-tool compartment.Key Features:Simple and secure neoprene saddle rail attachment,Vibration absorbing design keeps bag in place and out of mind,Unique design eliminates need for seat post strap,Small size holds 1x road tube and a small multi-tool,Medium size holds 2x road or 1x MTB tube and a small multi-tool,Colour; Black or White,Small: 30 in3 / 0.5L gear volume,Medium: 40 in3 / 0.6L gear volume.