Nickel plated cogs, Heat-treated, Polycarbonate glass fiber spacers, Double row precision bearings, Double pawl mechanism with 20 interface retchets. Available in 5, 6 and 7 speeds, frome 13 to 24, 32 teeths. Stack height 5sp ; 29.2mm, 6sp ; 31.5mm, 7sp ; 34.1mm