The Valken 140rd Thermold mid-cap airsoft magazine is constructed of durable hard polymer material, are lightweight, and can take a beating. The 6mm AEG magazine features a standard design making it great for all types of M4 magazine pouches, and compatible with most major brand M4 airsoft electric guns. No winding is required like hi-cap magazines. An airsoft speed loader is required to load BBs into these magazines (which is not included). We recommend our Valken speed loaders for use with the Thermold airsoft gun magazines.