Originally Posted by
Bill Kapaun
3/8 drive allen sockets.
Add metric if you prefer that type.
Also available in 1/4" square drive and, for really big stuff, 1/2"-square drive. I found most of the sizes I use (3, 4, 5 and 6 mm) are usually in 1/4" square drive format. The only 3/8" square drive bits I have are 8 and 10 mm.