The lower part of the Ritchey Comp Cartridge Integrated IS head assembly is equipped with stainless steel angular contact bearings that are filled with Ritchey grease. Material: alloy Stack height zero Head tube ID: 42, 47, 52 mm S.H.I.S.: IS42/30 (1⅛"), IS47/33 (1 ¼"), IS52/40 (1.5") IS42/30 (1⅛") bearing41.8/30.5/8mm 45°/45° - sealed cassette (ACB) IS47/33 (1 ¼") bearing46.9/34.1/8mm 45°/45° - sealed cassette (ACB) IS52/40 (1.5") bearing51.85/40/8mm 45°/45° - sealed cassette (ACB) Weight: 32g Colour: black