Fortis Manufacturing, Inc., Shift, Handstop, M-LOK, Carbon Fiber, Black M-Lok Mount Fortis' Shift Handstop integrates form with functionality. The shape works as a comfortable handstop when going with the thumb over method or even when reversed. Some prefer their pinky in the groove, others have found their ring finger to be comfortable. Find the grip that works for you, but whichever way you decide to grip it, the grip allows you to handle the rifle with confidence, and the organic design enables the operator to manipulate the rifle in ways that are not quite possible with other handstop designs.