The K22 X-TRIM is the rimfire little brother of the X-Calibur, and heavily borrows from its design. The slide, with the aggressive lightening cuts and angled serrations are one aspect. Just like with the X-Calibur, they provide a secure purchase for manipulating the slide. The Mk23 X-TRIM also features an optics-ready capability out-of-the-box just like the rest of our Mk23 lineup of handguns. These guns have been tested extensively with pistol red dots and they work reliably. However, we would caution against mounting too-heavy of a red dot optic because, at the end of the day, it is still a .22LR. The X-TRIM, like the rest of our 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 that are shared with the X-CALIBUR is the STI hammer, enlarged safeties, and oversized magazine release button. The new 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 side one and put on a low-profile, right-hand side lever.