No bigger than a decent sized key with a clip that allow it to easily attach to your keyring, this little tool is great. It has a tip that works as a screwdriver and box opener, a bottle opener, and a serrated edge that works to open plastic packaging. The tip even works as an allen wrench in a pinch. No issues with digging into my leg when kept in my pants pocket. I bought several-- partly because I expect the TSA to regularly confiscate mine, partly because I don't think it will last forever, and also for an inexpensive Christmas gift.
I didn't get it at REI, but they sell it:
https://www.rei.com/product/102803/nite ... gITaPD_BwE