SL421RI, 30 amp, 240 volt, 3 phase, 4 wire, fusible style bus plug, includes weather stripping for drip protection, type BEL / SL, UL Listed assembly, complete with UL Recognized internal switch and components, suitable for use with OEM Spectra Low-Amp Series industrial busway systems, accepts Class H, R and J fuse types, direct substitute, fit and function for OEM SL421RI, SL421RJI