This Enduro Integrated/Drop-In headset for 1-1/8" x 1-1/2" tapered fork steerer tubes features Angular Contact Bearings with chamfers, premium 440C balls and races, and 90% fill with high-pressure waterproof grease. This top quality Drop-In headset is built for long-lasting durability thanks in part to the high performance bearings that are guaranteed for as long as you own the bike.This IS42/IS52 Integrated/Drop-in headset fits bike head tubes with 42mm top IDs and 52mm bottom IDs, bearings with 36 /45 chamfers, and tapered (1-1/8" x 1-1/2 ) steerer forksFeatures top-quality 440C balls and races, dual-lip seals top and bottom, 90% fill with high-pressure waterproof grease, and are guaranteed for as long as you own the bikeUpper 1-1/8 bearing ACB 3645 1125 SS (also known as IS42, ACB30418K, and MH-P03K) with 30.5mm ID, 41.8mm OD that features a step down to just under 41mm at the top of the outer race, and a width of 6.3mmLower 1-1/2" bearing ACB 6808 SS (also known as HD 1404K, BAA0006K, MR-127, MR-196, MH-P25K, BAA1132, and TH MR019) with a 40mm ID, 52mm OD and a width of 6.5mmKit includes upper bearing cap, hidden bolt topcap preload adjuster, with 36 crown race and compression ringItem SpecificationsBearing TypeACBColorBlackCrown Race40Defined ColorBlackS.H.I.S LowerIS52S.H.I.S UpperIS42S.H.I.S. Stem Clamp Diameter28.6 Threadless Enduro Drop-In Headset Kit Headsets UPC: 195947058341