Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 28 1-2 found under Hanger Sliding Door by Richards Wilcox Inc. The National Stock Number assigned to this part is 5340007206122, and the Federal Supply Class is 5340 Hardware Commercial. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 28 1-2.