Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 20619 4 found under Gage Mask Safety Pr by A Vox Systems Inc. The National Stock Number assigned to this part is 1660009428507, and the Federal Supply Class is 1660 Aircraft Air Conditioning Heating And Pressurizing Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 20619 4.