Review on ZokMok Carbide Keyhole Diameter Hardened: Unbeatable Precision and Durability by Mike Walters

. There are much better quality bits for the price and you don't need this type, but all too often it's a good deal. If you use them you will need to increase the size to 1/2 inch. I suggest using a 1/4" bit and making multiple passes until you get full depth. Then use the 3/8 keyhole attachment to get the grove, then finish with 1/2. This is a set more than usual, but it's not terrible. I tried going from a 1/4 keyhole to a 1/2 keyhole and after about 10 uses the drill bit dulled and started burning the wood. I contacted the seller and they understood. They were able to send me another set and the step by step method gave pretty good results.