Armorer's part question

Posting this one for mowzerluvr. One slide is marked eagle 4 with no other markings and I'll presume is an armor's spare. The other I have never seen before is marked bsw with eagle and 0,2 on the back like so often seen on replacement barrels. Does the 0,2 denote a higher level of rework, say depot or just a dimension change or...?
Thanks,
Ken

Dimensional. You'll find similar markings on the bottom of front sight blades.

Cool part Ken, here are some armorer sight blades for comparison