5: five inch length
W: wire-cutting jaws (there at the base of the pivot)
R: "round," or curved, jaws, rather than straight, meaning the tooth pattern.
These are a very handy size. Now that I've managed to acquire enough tools to do things with the right tools 95% of the time, along with reaching the income stage that I own cars and such that don't require constant attention (so that many of the tools spend 95% of their time just sitting there waiting for action), these little ones are just about all I use except every once in a long while.