Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 42-25C87-13 found under Screw Train Pillar by Chelsea Clock Llc The. The National Stock Number assigned to this part is 5305007199109, and the Federal Supply Class is 5305 Screws. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 42-25C87-13.