Even the very best quality tool steel drills can't hold a candle to these - made for drilling into the toughest steels. The high cobalt alloy content is the secret. (The only thing they won't handle is tungsten carbide, and you'll very rarely find that you have to drill into that.)
Because of their relatively high cost, you'll want to save these for when you need to use them. But when you need them, you need them - right then, not days later. They are hard to find locally. Here they are to add to your toolbox.
Set contains
1/16" 5/64" 3/32" 7/64" 1/8" 9/64" 5/32" 11/64" 3/16" 13/64" 7/32" 15/64" 1/4" 17/64" 9/32" 19/64" 5/16" 21/64" 11/32" 23/64" 3/8" 25/64" 13/32" 27/64" 7/16" 29/64" 15/32" 31/64" 1/2"
That is from 1/16" to 1/2" by 64ths.