Avler 1/2" (.50 Caliber) Steel Bearing Balls for Slingshot Ammo (Pack of 100) Go to amazon.com Related posts Which is the best ball bearings? FeatureMaterial: Chrome SteelWeight: 8.4g each100% Round. No flat spotsSize: 1/2" Diameter (.50 Caliber) (12.7mm)Pack of 100 DescriptionMaterial: Chrome Steel. Weight: 8.4g each. 100% Round. No flat spots. Size: 1/2" Diameter (.50 Caliber) (12.7mm).