Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 43077 found under Packing Ring by Btr Valve Sealants Inc. The National Stock Number assigned to this part is 4820004006684, 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 43077.