Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 542 20 64-56 found under Parts Kit Safety Relief Valve by Husqvarna Outdoor Products Inc. The National Stock Number assigned to this part is 4820015892384, 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 542 20 64-56.