The MadBull Ultimate hop-up unit is a really innovative design for the
M4/M16 series AEGs. It allows easy and precise hop-up adjustment do to
the larger diameter wheel which has been relocated. The traditional
style hop-up units with the small adjustment wheel on the side are
usually either too hard to fine tune and rotate smoothly or too loose
and vibrate loose and back off from your idea hop-up setting. This can
be a real annoyance during game play.
Ultimate hop-up units are fully compatible with the MadBull LED Tracer
unit (optional) attachment which allows for a completely hidden tracer
solution. Negating the need muzzle mounted tracer units or tracer
magazines.3 Functions in 1:
(1) Tracer unit: You can attach a MadBull LED tracer unit on this Hopup
unit. This is an optional accessory and will be available soon.

(2) Chamber lock: With this new hop up design you will not have to worry
about losing and dropping several bbs with a magazine change. This new
design provides you with a way to keep bbs in your AEG and ready to
use and not on the floor and even better it stabilizes the top of the
magazine to ensure a secure and flawless feed of bbs into the AEG.
You can take out the oring if you dont like this function. This
function is designed by Brian Holt.

(3) Easy adjust Hopup: Compared to traditional Hopup, our Hopup can be adjust easily.