See a letter "A" on your drill bit? You're holding the first and smallest size in the letter-gauge drilling system. Perhaps unsurprisingly, this standardized series runs alphabetically from A to Z. On ...
I just got a set of Dewalt Titanium drill bits with the hope of reaming out a couple of holes that were too small. One hole was .49" and needed to be .5", and the other was .36" and needed to be .375" ...