Looks like the name comes from the way the hole on handguard looks like a keyhole.I think it make getting that type of rail easier to put on and get off.Like some stuff you hang on the wall with that type of back.
I can see the different options feature,but when you add sight and light get'sa up there in price.Not that they are giving the SL1 away @ $235.00.I still likey.
Got a e-mail from Bravo Co. on a alum/magnesium keymod handguard for a 5.56, not sure if they have one or a type like that for .308. Suppose to be strong and light.