The Valken 300rd Thermold Hi-cap airsoft magazine is constructed of durable hard polymer material, are lightweight, and can take a beating. This high capacity airsoft magazine fits most M4 or M16 style airsoft rifles, and holds 300 BBs. This AEG magazine also comes with a high quality spring and clutch system to ensure smooth feeding. You can find these airsoft magazines in black or tan colors. We recommend using our Valken Infinity BBs for use with this hi-cap magazine.