Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number NSL3961 found under Photocell by Silonex Inc Casco Products Company. The National Stock Number assigned to this part is 5980000113844, 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 NSL3961.