I've been carrying this Topeak multi-tool since the mid 2000s.





It's very compact, and there are no pointy bits that could puncture a spare tube. The rotating head means it can be used as a screwdriver or a wrench.

It was discontinued years ago, as all great products are. if I had to replace it, I'd probably get the Ratchet Rocket Lite DX:




The ratchet is overkill for roadside repairs, but the ratchet handle can be used as a screwdriver. Still, quite a bit bulkier.