Ritchey:

The CroMo Ritchey Comp Cartridge Semi-Integrated ZS Lower Headset features full complement stainless steel angular contact titanium-coated, sealed cartridge bearings packed with Ritchey high-webbing grease.

Material: alloy
Stack height: 2.8mm
Headtube OD/ID: 50/44, 55/49, 61/55, 62/56mm
S.H.I.S.: ZS42/30 (1 ?), ZS49/33 (1 ), ZS55/40 (1.5″), ZS56/40 (1.5″)
ZS42/30 (1?”) bearing: 41/30.15/7mm 45/45 – sealed cartridge (ACB)
ZS49/33 (1 ) bearing: 46/34.1/7mm 45/45 – sealed cartridge (ACB)
ZS55/40 (1.5″) bearing: 51.9/40/8mm 45/45 – sealed cartridge (ACB)
ZS56/40 (1.5″) bearing: 51.9/40/8mm 45/45 – sealed cartridge (ACB)
Weight: 40g
Colour: black