Description of Irwin Tools 1882784 Countersink Number 12
#12 wood Countersink. This product is highly durable. This product is manufactured in China. Tapered drill with widened flutes for drilling fast, clean pilot holes and ensures tight fit for screws. Adjustable four-cutter counter bore cuts and clears chips quicker for fast, smooth countersinking. Counter bore attaches to flats on shank with two hex screws for a secure fit and can be adjusted for controlled pilot hole depth. 1/4" quick-change shank reduces slipping in standard chucks and is compatible with all 1/4" quick-change chucks, including impact drills.
Inexpensive and it will work, I got it with Amana 55212 CT COUNTERSINK Carbide Drill Bit #12. Amana is 4 times more expensive but 10 times more expensive. If you only need to drill a few holes you can't beat Irwin, but if you have 1000 holes spend the extra money on Amana.
I gave it four stars because when used with shorter screws it is very difficult for a countersink to hold it in place further down the drill bit. I have found that I need to check the position after each hole. There's good flatness, but there's literally less than 1/4 inch of adjustment.