Draincock Nut

When I'm out in the garage using the "Air Compressor" once I've finished for the day and I want to drain my "Bostitch pancake compressor" the round knob they put on it has just enough knurl to be seen, but not enough to be useful!

This gives you a better grip and you don't need to find a pair of pliers, too open or close the draincock!