AC421R, 30 amp, 240 volt, 3 phase, 4 wire, fusible style bus plug, type BEC / AC, UL Listed assembly, complete with UL Recognized internal switch and components, suitable for use with OEM Armor Clad industrial busway systems, accepts Class H, R and J fuse types, direct substitute, fit and function for OEM AC421R, AC421RJ, AC1421, AC1421R, AC1421RJ