The waterproof outer pocket, e.g. for tools, first-aid-kit, bottle, purse etc., can be mounted to any ORTLIEB pannier (or to any other bag).Fast attachment and removal is guaranteed. The loop on the reverse side allows you to wear the outer pocket on your belt or to attach it to straps. The outer pocket in size S is suitable for panniers and small backpacks; size large is suitable for larger backpacks or dry bags.The outer pocket comes as a single bag and includes the mounting rails, a punching tool and a template.Available accessories: additional mounting rails for a second pannier