Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number XB1019 HW90 1B found under Regulator Thermostatic Temperatu by Emerson Electric Co. The National Stock Number assigned to this part is 4820016553495, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like XB1019 HW90 1B.