Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 524-521-22 found under by Marl International Ltd. The National Stock Number assigned to this part is 5980995514905, and the Federal Supply Class is 5980 Optoelectrical Devices And Associated Hardware. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 524-521-22.