The HK MP7 A1 VFC AEG 110 round midcap magazine.  Fits in the AEG airsoft MP7.  Has a magnet at its top that locks in.  Follower prevents the gun from dry-firing (also makes sure it uses all its BBs, none fall out!) when the gun is out of ammo.  This is an advanced magazine specifically made for this gun.  
Made by VFC
 
Mag is compatible with 2262070 HK MP7