This is a triangular pouch that can be attached to the main frame of a Brompton. It is a genuine accessory from Brompton. It can be used on older Bromptons, as well as the P Line and T Line. As shown in the reference photo, I purchased the "BROMPTON Puncture Pouch Multitool"... https://www.brompton.com/p/1612/puncture-pouch-for-a-c-p-t-line My main purpose was the multi-tool that came with the set. I already have another pouch and don't need this one, so I'm selling only the pouch. It has enough space to hold basic tools and one spare tube. To access the contents of the pouch, you don't need to mess with the fixing belt; you can open the lid on top by rotating it slightly (see reference photo). The material itself is water-repellent, so it seems unlikely that it will absorb splashes of mud, etc. The lid is opened and closed with Velcro, and the structure of the opening is designed to prevent normal rain from entering (it might get wet in a heavy sideways rain). This pouch is the same specification as the triangular pouch (frame bag) that came with the final CHPT3 model, but in a different color. ■ Weight: 46g (actual measurement, including mounting belt) ■ Size: 106 x 145 x 48mm (actual measurement, excluding mounting belt)