In Private Caboose Airsoft's Tippmann Tips & Tricks Video Series he does an in-depth review of the Tippmann M4 Hop-Up... "Hey Tippmann fans! This video is an in depth look at 3 of the styles of hopup units I have used extensively.  This video will explain how each of the units work, the pros and cons of each, and how I feel that each unit can be used to it's full potential.

This is entirely my opinion, which was formed from rigorous testing/play with each hopup unit."