POWERTEC Drill Bit Stop Collar Kit with Imperial System Size Markings - 7 Piece Set Adjustable Depth Stop with Allen Wrench - 1/8", 3/16", 1/4", 5/16", 3/8", 7/16", 1/2” (71491)

Excellent product very happy

I agree with others that this product is garbage and a waste of time for all, including Powertec. The problem is they are impossible to tighten without stripping the allen screw. Anyone who 'tests' these will see it is obvious the relief cut is too shallow on the color and no way to have them tighten. I can assume the larger one may work but 1/4" did not. They deserve the returns as they do not seem to be listening to customer feedback. Maybe they are just trying to dump bad inventory.

Rubbish. Wish zero stars was an option.

I needed to drill hundreds of holes to a specific depth into aluminum blocks and used one of these on 6mm drill bits. It held tight and worked well. It was easy to move from one bit to another.

Por mucho son mejores que los que tienen dos tornillos para ajustar la altura, con estos no se daña la broca

Awesome product from Taiwan. I've been using these for a year now and have had no issues. Much better than the set screw type. Just use to correct size drill bit and they work perfect. The collars are clearly marked.