Deep Fire has put together a new hop-up system for M4 AEGs, that is similar to the system used in Systema PTWs. It does not use a traditional bucking or nub, instead using a totally different system including the inner and outer barrels. This hop-up system is installed in Deep Fire's "Professional" line of M4 AEGs.
-Very robust components ? machined aluminum, high quality O-rings, etc
-Incredible consistency, both with FPS and with accuracy
-Keeps its desired setting very well
-Less wear and tear due to the different design
-The body of the hop-up absorbs shock and transfers it into the upper receiver