The Compacts are indeed tiny. Woven polyester construction is tough, and the seams are stitched well on the inside for extra durability.
The back plate is bendy and the mounting system is very simple - open-ended hooks fit over the rack (10mm diameter) but they're non- adjustable, so you'll need to check they fit with your rack.
An elasticated cord hooks onto the legs of the rack to stop the pannier jumping off, but it's a bit fiddly to fit and remove. There's a mesh pocket inside the lid, a drawcord main compartment and a rear reflector. Unfortunately, no cape is provided and the fabric isn't waterproof.