The Mini is the only seat pack a summer roadie will need.
The Castelli Undersaddle Mini is just the perfect bag that any road rider has a use for. Super compact this fit and forget under saddle, seat-pack can be crammed with a couple of (road) inner tubes a multi-tool, a spare link and a few £10s. Everything you could possible require on a ride.
The strap uses a magic moulded hook and loop fastener that can be trimmed at home and that wont fur your shorts.
The Mini bag is also weather resistant as is the zip. (OK its not totally waterproof but its better than most) the zip pull sits in a little cave so it stays silent and doesn't open mid ride. The rear wordmark is reflective and the lining is in a pimp corporate red. Could you ask for more?
Possibly the greatest acolade for the Castelli Undersaddle Mini is you forget its there.