PF9SS vs PF940SC: which small Polymer80 frame for a carry build

Both are the small Polymer80 frames and both get called "subcompact" in forums, which is how builders end up with the wrong slide. They are different guns.

PF9SS: single-stack, Glock 43 pattern

The PF9SS takes Gen 3 Glock 43 slides, barrels and parts and runs 6-round G43 magazines. It is the slimmest frame Polymer80 makes, about an inch wide at the grip, and the one to choose for pocket or appendix carry where width matters more than capacity. It does not accept G43X or G48 slides.

PF940SC: double-stack, Glock 26/27 pattern

The PF940SC takes Gen 3 G26 and G27 slides and runs G26 10-round magazines, or G19 and G17 magazines with a grip sleeve. It is wider than the PF9SS but shares magazines with a compact or full-size build, which matters if you already own a PF940C.

Finishing

Identical process: three pin holes, rail tabs, barrel block. The PF9SS jig is smaller and the tabs are thinner, so file carefully. Neither is harder than the compact frame.

Which one

Slimmest possible carry and you do not own other Glock magazines: PF9SS. Shared magazines with a bigger build, or you want more than six rounds: PF940SC. If you already own a G26 or G43 slide, that decides it for you.