The G&G GTP9/SMC-9 Extended Gas Magazine (Part No. G-08-181) is a 50-round high-capacity metal magazine designed for both the GTP9 gas blowback pistol and the SMC-9 GBB carbine. 
 
Key Specifications
Capacity: 50 rounds of 6mm BBs.
Compatibility: Exclusively compatible with G&G GTP9 and SMC-9 series airsoft models.
Material: Full metal construction, including alloy feed lips and a metal follower.
Weight: Approximately 580g empty, or up to 650g with packaging.
Power Source: Designed for Green Gas, with recommendations for Red or Black gas in colder conditions.