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There are at least two different lengths of the 20s screw driver bits, and there are differences in the lengths of the two main lengths. These show up in the 26-28 cats. The longs ones I have are not date coded. The long ones have slots in the tips to fit inside the screw. The cats show four sizes, but I know of at least six sizes, five are shown it the pics. the shorter ones I have are all 1927 date codes. I only know of four sizes (widths) of them. So if you have some different ones, or long ones with date codes, post a pic.
The drivers for these are very rare, there are variations for these, so, if you own one post a pic so we can see the differences.

Cool set of screw drivers. Was there also a wooden handle (driver) sold that did not have the hole for the sliding bar?

yes, some of them did not have the hole. Also there is a 9/32 driver from this era with a wood handle.

Here is another driver, somewhat different, no hole. This belongs to Mike K.

Here is my example. Mine is the exact same version as Mike's, but with the hole through the bolster. The raised lettering on the bolster is almost completely worn off on mine, with just faint remnants of "Snap on" and "Milwaukee" still visible.