Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B4381 found under Boot Spring Assembl by Kirkhill Ta Co. The National Stock Number assigned to this part is 1680002364091, and the Federal Supply Class is 1680 Miscellaneous Aircraft Accessories And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like B4381.