I got the Schrade Key Chain Pry Tool as a birthday gift and it's been on my keychain since. It's about 3.25 inches long and about an inch at its widest. It has several tools including: pry tool, bottle opener, seat belt cutter, screw-driver, and a wrench driver that accommodates a variety of bolt/nut diameters.
It has a hole for attaching to your keychain, but also comes with a lanyard if you don't want to attach directly to your keyring.
The seat belt/cord cutter is recessed so you shouldn't cut yourself unless you really try, but it sometimes can get caught on your pocket on the way in. Also, if you have young kids, be careful if they play with this as their fingers may be small enough to fit in the blade area.
The thing I like most about it is its weight. It is made of titanium and weighs 0.5 oz., about the weight of 3 quarters! I have had several other keychain tools, but they were all either too heavy or too bulky. With the pry tool on my keychain, I hardly notice the difference in my pocket. — Stuart Peterson