championChampion CSK-SET-5 Zero Flute 82-Degree Countersink Set, 5-Piece

These are some of my favorite countersinks. Use a little cutting wax and cuts aluminum storefront with no issues. Excellent quality.

Clean holes,easy to sharpen does what its supposed to do.I use these on wood and have not been disappointed. I have not used these on metal so I can not give a review on how they work for aluminum

This is a great countersink set for woodworking. Great results.

Considering this set of five countersinks costs less than one good one, I'd say it's a very good value. I've used several of them to countersink aluminum and steel tube stock. They chew out a good angle very quickly without leaving burrs or chattering (like a "normally" fluted countersink). In fact, I've even used the large countersink with a very light "tap" to instantly de-burr holes. Even in a hand drill, they're very stable.I can't comment on the durability yet (I've probably only sunk about 20-30 holes), so if the price reflects any failing in these bits, it's probably their longevity.The 82-degree angle is the standard recess angle for SAE machine screws with recessed heads (called "flat head" screws by people who work with fasteners). Metric flat-head fasteners are (usually) recessed for 90-degree countersinks.The container is cheap, and probably isn't intended to be your day-to-day organizer (just enough to keep the bits from marring each other in shipping).

These are small, set is useful for 3/8 holes or smaller, work great