Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 18-28 found under Spring Set by Kirby Morgan Dive Systems Inc. The National Stock Number assigned to this part is 5360011724060, and the Federal Supply Class is 5360 Coil Flat Leaf And Wire Springs. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 18-28.