Lezyne Caddy Sack V2 - schwarz

It is perfect. I can put inside ID, bank cards, keys, 1 CO2 cartage and CO2 system. Just enough for minimum kit.

The past reviewer is right. The iPhone 4 does fit though, but with not much more than a card and keys. You either can bring spare essentials like tube, patches, tools, etc. or just use it as a slim waterproof wallet. Not both. Definitely the iPhone 5 will not fit. If you want to carry your smartphone along with the rest of your essentials, get the M size.

Waterproof, and lightweight.

but beware that the stated sizes is not correct. An iPhone wont fit into the smallest even if it should, given the dimensions.