40-Series Zero Stack headsets set the standard for performance durability and value. Drawing from the premium 110-Series design the 40-Series includes all the features necessary for a durable lightweight long-lasting headset.Sealed ZN40 cartridge bearings6000 series alloy cups and materialsSteel crown race with integrated sealsInterlok spacer compatible TECH SPECS Color Black Lower Stack Height 4 Bearing Type Cartridge Crown Race 30 Weight 88 S.H.I.S Lower ZS56