Designed for use in standard 1 5/8" channels, these strut accessories and fittings are 100% stainless steel.Material: Channel Nut - 316SS, Spring - 302SSStandards: MPIF Standard 35, ASTM A313Part Number Part Number without Spring Thread Size 5911 5901 1/4 - 20 5912 5902 5/16 - 18 5913 5903 3/8 - 16 5914 5914 1/2 - 13 5915 5905 5/8 - 11 5916 5906 3/4 - 10