Bi-pods a TDI, its a real steel part and its a top bit of kit. The legs extend and are adjustable too. I bought that a few years ago, and its indestructable.
Thats the standard handguard for the M16 with a 203 on it. Battery is in the stock. The M4 has the battery under the front handguard. The SR16 also has the battery in the stock.