The 2.7 Square Bit Screwdriver
I've been using square-drive screws for years, and I have what I thought was a complete set of bits: Sizes 00, 0, 1, 2, 3, 4, and 5. (I've never used the #5) Now I see there is a size 2.7. From photos on line it seems to be sized between a #1 (which measures about 2.3mm) and #2 (measuring about 3.15mm). So maybe 2.7 is its size in millimeters. What is it for? Who came up with this? Am I ever going to need one?