It, too, was introduced only a few years ago, in 2014. The M-LOK rail system ('Modular Lock') was developed by Magpul in response to VLTOR's KeyMod system. They're conical and provide additional tension when fully tightened. The other secret to ensuring KeyMod attachments stay in place rests in the lugs themselves. In order to prevent the rail or accessory from coming loose from recoil and impacts, the slots and lugs face the muzzle. KeyMod attachments work probably exactly how you imagined they might: Specially shaped lugs, designed to provide tension when slid into the key-shaped slots, secure either a rail section or accessory directly to the handguard. No 'male' connectors means no pointy bits when gripped. The bulky connections come from accessories, not the rail. They don't leave unnecessary 'rail' sitting around. Negative/female rail systems like KeyMod and M-LOK are: This affords a few advantages over the ole 1913 setup. KeyMod is 'open source', meaning any manufacturer in the firearm industry can freely develop handguards or rails that utilize KeyMod without having to license or pay royalties to VLTOR. Instead, it's a 'negative' or female rail system, where as the Picatinny rail system is positive, or male. The KeyMod system does away with the external, raised rails and pointy edges. You know that as the Picatinny rail, and it still remains one of the most popular - albeit heavier, bulkier, and less comfortable - rail systems on the market. It was intended to replace the military's tried 'n true MIL-STD-1913 rail. But first, let's give a quick summary of what each system is, exactly. KeyMod is a rail system developed in 2012 by VLTOR Weapons Systems in Arizona. You'll find the measurements you need below and more importantly, we'll review an in-depth comparison the Military's own SOCOM conducted. We need to give a shout-out to The Broad Side self-defense shooting publication for some of the pictures below. Which is better for all your accessories, optics, bipods, flashlights, and lasers? KeyMod or M-LOK? What are the differences? We're breaking down both.

Like the kind you'd find on those steel shelves in the garage. One's a bunch of slats, one's a bunch of keyholes.

B5 systems keymod accessories