I'm not sure how to phrase this so it may be confusing.

I have an 2 impact drivers, Milwaukee and Bosch. They both have a 1/4" bit locking mechanism.

I guess I have 2 types of bits: 1 where the bit doesn't have a collar (say 1" down from the bottom of the bit that inserts into the driver). The other where the bit doesn't have have a collar and is hex shaped through the length of the bit.

The ones with collars can be bits but in particular the ones I'm using are: 1) adapter that accepts bits w/o the locking notch, 2) adapter for sockets (and different extension lengths).

The distance from the end of the bit to the collar is short for the adapters I have - about 1". This works on the Mil but I guess it's too short for the Bosch - I can't get the bit to lock.

Are there different standards I need to be looking for as I buy these adapter bits? I've never noticed this before. Or is the Bosch just not very accommodating in it's design - it's only mean to accept bits that are hex through the length of the bit - no adapters allowed?

It sounds to me like the Bosch is not very accommodating in it's design. Bosch does some odd things from my experience.

I have the same Milwaukee driver. All of my adapter/bits fit just fine. It's an awesome tool...just stick with that one.

I was attracted to the Bosch for the built in 1/2” socket adapter and also locking 1/4” hex bit. I didn’t know about the collar length issue. A bit 1 1/8” end to collar is okay, bits with 1” end to collar don’t lock. 1/8” is making all the difference. I’ll figure it out. Just wasn’t sure what to make of this.

Didn't Bosch have a set of "impact rated bits" that they marketed a bit ago?

I wonder if they are just different enough to cause the issue you are seeing with the regular collar bit?