Airtech Studios G&G ARP9/ARP556 Battery Extension Unit (Color: Black)

"Awsome I use it for a cm16 raider 2.0e

"you need this if you have a arp9 because this will give you more space and a less of a chance of breaking wires but the price is high

"This is a must buy if you have arp9. it lets your gun hold bigger battery and gets rid of the stock wobble.

"Objectively improves the arp9's stock. A must buy if you're keeping the original stock

"Sturdy material with no creaks or slack. Generous space after adding it to a 556 and can now run a 1450mAh 7.4 with room to spare even with the connectors and MOSFET.

"This fits well and definitely makes it easier to put a battery in the stock. Looks good, too. If you don't need the shortest length possible, pick one of these up and make battery installation easier.

"It works but for some reason I was shipped a red one which doesn’t match my gun at all!