19PCS Tungsten Carbide Hole Saw Kit, 5/8" - 2-1/8" TCT Hole Cutter Set with Titanium-Plated Pilot Drill Bit for Metal, Stainless Steel, Iron, Wood, Plastic - Matte Black Finish

These hole saws are more like annular cutters than traditional hole saws. The teeth cut cleanly, with large gullets to aid in chip clearing. The walls are thinner than the teeth, so there is no additional friction to generate extra heat during the cut.I have been using fairly nice bi-metal hole saws to cut openings of several different sizes in 6061 aluminum boxes. No matter how carefully I go, the moment eventually comes that the teeth bind in the aluminum, which breaks if I am not quick enough to stop the drill press. These cutters are dramatically outperforming the ones I have been using. They have managed several times as many holes and, as yet, show no signs of dulling or wearing out. Note that I AM using cutting fluid as well as watching my speed and feed carefully.I see no reason why these teeth cannot be resharpened (with a carefully made jig, to maintain accuracy) to prolong the life of each hole saw. While these are not super high-precision, they do perform to much tighter tolerance than others I have used, and leave my work looking clean and professional.

So far this set has been perfect

I am just a hobbyists, working in my garage, so I don't have the budget to buy a fancy set of hole saws, but this does an excellent job for the cost. The teeth have stayed sharp so far, and they make clean holes.