Matrix CQB-R Complete Front End Kit For M4 / M16A2 series Airsoft AEG

"The upper rail mounts over the gas tube with blocks held by roll pins but they can be punched out.
The the rail is only 6.5 inches so it doesnt accept standard AR furniture without some modifications.
The rail covers provided are way too tight to use.
The assembly is all metal and will fit into a cyma receiver.
The bolt or pin in the top of the barrel towards the hop up is larger that the channel in the receiver but the channel can be filed down a little to accept it.

"This is very high quality. The only bad things is that the pin for the gas tube is loose so the gas tube moves around. Also, the rail covers are very tight on the rail and the rail is a little loose. Other than that it is great.

"Looks great, but rattles around when shaken. This rail system requires the front sight/gas block to stay on. The delta ring comes loose when the gas tube isn't installed.