G&P MOTS 12.5 inch Full Keymod for WA M4 GBB (Sand) m4 "machine pistol model 5") is

"machine pistol model 5") is a 9mm submachine gun of German design

AEG Power Source Up to 9

There are holes in the end for 'ventilation' but it's just for looks in this case

Metal Construction  Design for Replace the Original Extended Charging Handle  Suitable for GHK AK Series Airsoft Electric Gun GBB Rifle

Fully Compatitible with Aftermarket Airsoft Guns using V3 Gear Box

G&P MOTS 12.5 inch Full Keymod for WA M4 GBB (Sand) m4 "machine pistol model 5") isG&P MOTS 12. 5 inch Full Keymod for WA M4 GBB (Sand) Full Metal Construction Suitable for G&P GBB Metal Body & WA M4A1 Series 20mm Top Rail (Length: 317mm) & 20mm Under Rail (Length: 80mm) With Keymod System Length: 317 mm