QON OEM mounting bases are for the mounting of plug on QO, QO GFI, QO AFI and QO EPD circuit breakers. These OEM mounting bases are available in single and three phase versions. This QON OEM mounting base is for a main lugs of 125 A at 240 VAC single phase. This mounting base has 20 spaces for 1 pole. The main breaker will accept 4 AWG to 2/0 AWG copper or aluminum wire. The QON mounting base is UL component recognized. The QON mounting base is UL component recognized.