I used this probably twice before I decided I’m not tall enough to appendix an X300U.
This fits the Glock 19 Gen 3-5 (and 23 Gen 3-4) and both the A and B X300U. I just had to select something for the build options. It has soft loops for a 1.5” belt, a full guard, cut for an optic, and fits suppressor sights.
Price is $60, free shipping or picked up in Fairfax.
https://imgur.com/a/cpbv3Vd