26 blades made of hardened spring steel.Dual marked for both imperial and metric sizes.Thumb notch design of blade protector to air in removal of blades.Chrome plated steel protector with locking knurl nut.Blade length: 90mm (3-1/2")Blade width: 12.7mm (1/2")Thicness range: 0.0015" - 0.025" (0.04 - ..