I am a schoolteacher I always carry a SAK , I use it for unlocking doors to let teachers out when the kids have pinched the doorhandles. The screwdriver fits neatly into the little square hole where the handle fits , I get the door open in 2 seconds flat. I used to lose my knives until I tied a long bit of cord to one end, and somehow this prevents them from dropping out of my pocket. It is also useful for garrotting the kids who lock teachers in classrooms.

Jack The Lad