Additional Efergy Wireless Power Monitor sensor with earplug style connector Compatible with the Efergy Elite & Elink energy monitors For monitoring 3-phase supplies Attaches around a cable of a diameter up to 12mm Additional Sensors for use with the e 2 Elink Order Code N41HG & Efergy Elite Order Code N26GG energy monitors. Both models of energy monitor are supplied with one sensor. If you are operating a 3-phase supply then you will require two additional sensors. This is the standard sensor & will attach around a cable of a diameter up to 12mm.