Airsoft Pro 7mm/9mm Stainless Steel Spring Guide for L96, M24, M99, MB01. Sniper rifles. A brand new type of steel spring guide that allows the use of classic 7mm springs and stronger 9mm spring springs. Inner steel guide with the bearing has outer diamater 7mm. Once you've put on the sleeve, you can use a 9mm upgrade spring (means inner spring diameter). Axial bearing makes pull back much smoother, because of limited spring rotation. This solution also increases the durability of the set - lower friction and spring stress. The spring guide is made of stainless steel with a perfectly smooth surface. COMPATIBILITY: Spring guide is suitable for APS Type 96 system. Well MB01,04,05,06,08,13,14 CA / SW M24 SW M99 E&C L96