Well designed bag sans the rear clip. The bag is very secure and the full wrap velcro does a great job of keeping the bag from swaying under the saddle bottom. The elastic post strap is low profile, won't mar up the Thomson etching that is under so many of our rear ends, and holds tight on my 31.6 dia post. Should have zero issue holding a 27.2 post also. Really like that there is no velcro on the post strap which tends to snag bib-short legs.
I can cram, 1 std (not ultra-light) 700x18-25c tube, (2) 16 gram CO2, 1 micro inflate head, micro tool, 2 tire levers, and 2 insta-patches inside. Not much extra space beyond that for anything beyond a few wadded up dollars. An ultralight tube would allow for either a 3rd tire lever or perhaps keys.
The rear light clip is more of a urathane/silicone loop so the rear flasher (PB superflash) kinda just flaps around in the back and does not really point straight back nor does it stay still.
Overall recommend and will be buying more