This is what I like to refer to as an incredibly nifty device and I will tell you why! It's a Hop Up Chamber with a sensor to detect whether there are any BBs left and if there are none, it'll send a signal to the smart control unit, which it's connected to, telling it to stop firing so you don't end up firing blanks! Clever eh?
That's the short version. Allow me to get to the nitty gritty bits. The Hop up unit is made from a Shock Resistant Reinforced Technopolymer, which sounds like a Daft Punk album, making it optimized for high performance hop up rubbers. It's adjusted with clicks so you can alter the hop up with precision.
The ASHU (Bless you...) Hop Up unit is for all AR15/M16/M4 AEGs with ASCU. When it's connected to the ASCU, the ASHU (Bless you again...) detects whether the magazine is empty and if it is, it'll stop the AEG from dry-firing. Because firing blanks makes the AEG feel inadequate... But once you press the Bolt-Catch, it'll resume firing!
Now the ASCU Gen 3. This is what the ASHU (I'm really sorry, bless you for the last time!) is connected to. It's so small that it fits inside a Version 2 gearbox where the trigger sits and it acts like a MOSFET system making your AEG fire with precision which could be compared with a PTW.
You can change firing modes such as:
Semi + 3 Rnd Burst + Full Auto
Semi + Full Auto (The usual)
Semi + 3 Rnd Burst (Like a real M16)
Semi Only (If skirmish areas have a certain rule)
It comes with a manual with direction on how to change modes. It's within the AIRSOFT SMART CONTROL UNIT USER MANUAL section under 'Coosing Fire Mode' which I guess means Choosing Fire Mode.
It's all computer controlled and has sector gear monitoring so one trigger pull is a complete cycle making it have a realistic, crisp trigger. It's compatible with LiPo, LiFe, NiMH,NiCd from 7.2 - 12 Volts.