Once upon a time I had a great SAK, but I'm blowed if I can remember the name of it. It was approx the size of a Spartan but it was unusual in that it had a locking blade. Unlike modern SAK lockers this one had a metal push tab to unlock blade mounted on an edge of knife (near folded main blade if memory serves). All the modern SAK locking models seem to be the larger size, with a sliding plastic unlock button and for me they're just too big to put in your pocket and forget. The beauty of the one I'm trying to describe above is that its the 'standard' SAK size, but with an excellent locking mechanism.
If I can find the name of it finding one will be a lot easier obviously.
If I can find the name of it finding one will be a lot easier obviously.