Very well designed, very well made. The entire block is a bit longer than any others I've tried, which is good as the drill bit can be set to a shallower depth. I tried a Timberline locking ring and didn't like it because it uses a different size allen wrench. Allen key (1/8). Less allen keys to keep track of. I use it for #8 screws, 3/4 length, 1-1/4", 1-5/8", 2"