Kat wrote a review of SciCon Elan 210 Seat Bag on June 3, 2015
Familiarity: I've put it through the wringer
It works well enough, but this is definitely a diminutive seat pouch -- you're going to have to make compromises if you're used to carrying around a more luxurious flat kit. I find the velcro to be pretty secure -- in that the bag has never come loose -- but I occasionally get some rattling from the bag against the saddle rails no matter how tight I cinch it.
FYI, I can juuuuust barely fit one skinny tube, two small levers, one CO2 cartridge, an inflator, and a patch kit. I'd love a TINY bit more room for either an extra cartridge or a multitool, but the above has been sufficient for the vast majority of my rides.