This Passport penknife-style block squeezes in 2, 2.5, 3, 4, 5 and 6mm Allen keys, flathead and phillips screwdrivers and gets bonus points for a T-25 Torx wrench and (if beer's your thing) a bottle opener built into the shell.
We wouldn't trust it for heavy wrenching but it's fine for emergency tightening of loose bits on the trail. The price is good too.
It fits nicely in the hand, but on balance we'd rather have a 8mm Allen key and spoke key in the sideplate like you get with the Lifeline's multi-tool (£8.99, www.wiggle.co.uk), as these would prove more useful in the long term, even if it meant less beer was consumed.
The chromoly-vanadium tools are decent quality, and the whole thing feels well put together.