The K22 X-TRIM is the rimfire little brother of the X-Calibur, borrowing heavily from its design. The slide, with aggressive lightening cuts and angled serrations, is one aspect. Just like with the X-Calibur, these features provide a secure grip for manipulating the slide. The Mk23 X-TRIM also features an optics-ready capability out of the box, just like the rest of the Mk23 lineup of handguns. These guns have been tested extensively with pistol red dots, and they work reliably. However, they advise against mounting too-heavy a red dot optic because, at the end of the day, it is still a .22LR. The X-TRIM, like the rest of their rimfire pistols, is also equipped with the two-spring system, which makes it ammunition agnostic. A notable feature is that the K22 X-TRIM fits the same holsters as the X-Calibur. Other features shared with the X-Calibur include the STI hammer, enlarged safeties, and oversized magazine release button. The hammer is a throwback to the first GRAND POWER pistols imported to the US by STI. The safety levers can be swapped out for low-profile ones, or you can keep the large left-hand safety and add a low-profile, right-hand side lever.