Thank you for viewing. This is a TOPEAK saddle bag. It's the type that attaches to the saddle and seatpost with straps, making it easy to install on any bicycle. The capacity can be adjusted with a zipper, making it convenient. How about it for road bikes and cross bikes? ● 1200 denier polyester (DuPont Teflon coating) ● "Strap Mount" attachment/detachment system ● Compatible seatpost diameter: Ø27.2～34.9mm ● 3M reflective tape ● Includes a clip holder for TOPEAK rear lights ● L200 x W110 x H120mm ● 0.98～1.31ℓ ● 130g