Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 57-21-324 found under Light Emitting Diode by Osi Optoelectronicsinc. The National Stock Number assigned to this part is 5980012038289, 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 57-21-324.