Picatinny Rails
A Picatinny rail is a standardized mounting rail with a flat top and evenly spaced cross slots. Scope rings, lights, bipods and battery mounts all clamp to it. This section adds that standard rail to a KeyMod or M-LOK handguard, so those accessories have somewhere solid to go.
Check the slots. Picatinny slots are all the same width and evenly spaced, about 0.394 inch center to center. Weaver slots are narrower and the spacing can vary. Most Weaver-style mounts fit a Picatinny rail, but Picatinny mounts don't always fit Weaver. These sections are Picatinny, with numbered slots.
The rail profile is standardized, so a Picatinny mount from one maker should clamp onto a Picatinny rail from another. What differs is the length and how the rail attaches to your rifle. This one comes in 3, 7 or 11 slots and bolts to either an M-LOK or a KeyMod handguard.