There is one main compartment, with a plastic stiffener to keep tools from poking through. There is a flap of material on the inside bottom of the opening, which prevents small items from inadvertently sliding out when the bag is opened. The reflective piping helps with visibility. The front velcro loop secures the bag, so there is little movement. The velcro tension strap around the bag attaches under the saddle rails and allows you to tighten your load to keep things quiet. The size of the bag was chosen to keep a sleek under-saddle appearance, but maximize the volume available.  The bag is large enough to fit a mini-tool, 2 CO2 cartridges, spare tube and tire tools, with room left for a PowerBar.
Size: WxDxH =14x9x13 cm (5.5x3.5x5.1 Inches)
Universal mounting under any saddle
Silent red cord pullers, with plastic crimp
Reflective piping, SRM woven label inside
2 strap fastening system
Black body and side material