A brilliant tool that surprisingly few people seem to know about.
Stepped shaft to create an accurate hole for 3 common plug sizes, 5mm, 6mm and 7mm, they don't create the dust that a drill makes and is just as quick as a drill to use, so for commercial jobs that may have undergone a "sparkle clean" you don't need to waste as much time cleaning up after yourself.
I currently have 3 of these, one of which did suffer a split handle (since repaired and still works fine) an intact one that I use daily and a brand new spare just in case. Basically I would NEVER be without one in my bag.
They are inexpensive so I would tell anyone to give them a go.