A Stanley auger bit depth stop! Is it necessary? Not really. Does it work much better than just using masking tape?
The Stanley auger bit depth stop is very handy when working with dowels.
It can slip if one isn't careful about stopping when the depth is reached. Since for most of my work is with 2" dowels it is easy to regularly check the stop's setting against a dowel or another method of gauging.
I usually drill away until the gauge starts hitting the shavings and then take another turn or two. If one bears down to hard and continues it can scuff the work.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)