This is the (optional) Rover Rain Cape designed for biking. It's nicely made with strong webbing and a reliable buckle and assembled by local garment makers. It fits through the belt loop that's on the inside back of the Rover.
Waterproof, lightweight, and packable- the Cleverhood Rover Rain Cape will save your butt (or at least your clothes) from the rain. Now available in the improved 2.0 version!