MLOK system and picatinny rail system

Hey all,
New here and about to do my first build. I purchased a kit with an MLOK hand guard and am wondering, when purchasing accessories such as an optic, does the accessory have to be specifically designed and clearly marked as “MLOK” compatible? Or do most accessories/optics fit this system.

It depends. Most mlok ready handguards have picatinny rails up top, and mlok on the sides and bottom. If there’s a pic rail on top, you can use pretty much any optic mount.

In either case, the optic shouldn’t go on the handguard anyway, so it’s actually kinda moot, but your back-up sights would still need a pic rail mounting solution. I don’t know of any that mount using mlok.

Other accessories, such as lights may also require a pic rail. In that case you may have to buy a rail section that attaches to mlok if you want to mount it anywhere but on top.

I like the ease of mlok, and even keymod (which is all but dead), but I always laugh that we got rid of pic rails only to have to buy pic rail sections for some stuff to work.