This is a spare, solid 50 rounds Gas Magazine made specifically for the Thompson M1A1 GBBR. There is plenty of space in the gas reservoir to go through all 50 rounds with no problems!
 
Item Weight (gram) 390g
Major Color Black
Bullet Type 6mm BB
Magazine suitable for THOMPSON M1A1 GBB Rifle (WE/Cybergun)
Magazine Type Standard
Loading Capacity 50 Rounds