Picatinny Rail

Named for the US arsenal that formalised the MIL-STD-1913 spec, the rail's raised ridges and regularly spaced slots let a compatible mount's crossbolt or lever clamp down at any position along its length, giving genuinely universal compatibility across manufacturers rather than a proprietary fitment.

Even handguards built around M-LOK or KeyMod slots almost always keep at least a short Picatinny section on top for the primary optic, since so much of the accessory market — irons, red dots, scope mounts — still assumes a Picatinny interface as the default.

Rail covers are a small, cheap accessory worth considering, since bare Picatinny slots can be uncomfortable against a bare hand and their sharp edges wear on gloves faster than a smooth covered section would.