Yup.The metric drive sizes are:
I according to Wikipedia, there also are 25.4, 38.1, 63.5 and 88.9 mm.
Socket wrench - Wikipedia
And before you yell and scream, those ARE metric sizes. Real, actual metric sizes! You can find them on any metric scale, caliper, or micrometer.
If it ain't broke don't fix it. No need to complicate things adding more drive sizes.
In all seriousness - it goes 1/8", 1/4", 3/8", 1/2", 3/4", 1", 1-1/2", 2-1/2" drive then you've got funny stuff like spline drives.
Been that way for a long time and it's whats already in everyone's toolboxes
The only time I've seen 1/8" square drive was in a Snap-On catalog.
Sent using Morse code on - .- .--. .- - .- .-.. -.-
I can't think of a single real world application where I'd want an 1/8" drive socket on a driver handle. You can a set of small nut drivers and be better off.I bought a couple of the Snap-On 1/8 drive sets just for fun. One set came with one duplicate socket that the dealer had to replace with the correct size, though they do not sell individual 1/8 drive sockets.
Long ago, Snap-On also made 9/32, 7/16 and 5/8 drive sets. The 5/8 drive actually caught on for industrial impact wrenches and other companies made them, along with adapters to use 5/8 sockets on 1/2 and 3/4 tools. Supposedly, the 9/32 was only sold to the US Government agencies to discourage theft. A guy at work had a full set of chrome plated 7/16 tools that must have been bought in the late 1940's or 1950's. He said they were supposed to replace both 3/8 and 1/2 sets to save money and tool box space. He also pointed out that he never got asked to loan out a socket. I have never run across any other 7/16 tools.