Matthew Pizzawrote a review of Timbuk2 Bicycle Seat Pack on October 26, 2015
Familiarity: I've used it several times
This bag is just big enough, but not too big, to hold your tools while you're out and about. I have; a spare tube, 3 tire levers, and my multi-tool in there at all times...JIC, and they all fit in there no problem. The bag is low profile and has three attachment points to make sure that it is really secure on your seat post.