The G&G GR16 PLAStic magazine V1 is a 300-round high-capacity airsoft magazine made from durable polymer.
 
Product Details & Compatibility
The magazine (also known as the G&G GMAG-V1) is designed primarily for G&G M4/M16 series electric airsoft rifles but may be compatible with other M4/AR15 AEGs. 
Capacity: It is a high-capacity (hi-cap) magazine that holds 300 rounds of 6mm plastic BBs. Mid-capacity (mid-cap) versions holding 120 rounds are also available.
Material: It is constructed from a durable and lightweight polymer/plastic composite material, with textured surfaces for improved grip. Some models incorporate a rubberized side for enhanced handling.