That's a 3/8 paddle bit through 1/8 acrylic. I happened to be working with acrylic tonight. I'm building my sump. Figured I would get it nice and close to the edge to show how well they work.
Note that when they get small enough (at least the set I have) they stop having the points on the edges of the cutting face and go to just a straight wedge shape. Both work, but the sizes with the points on the outer tips (kind of like a brad point drill) work better than the ones without.