Contactors are an essential piece of kit for anyone using an HPS Growlight with a timer. A Contactor is activated by the timer and the contactor routes the power to the light, bypassing the timer. Without a Contactor, timers will routinely melt or lose timer function(usually the light stays permanently on). Powerstar are a reliable heavy duty contactor in three sizes.*1kw Powerstar 1 Way*2 Kw Powerstar 2 Way*3 Kw Powerstar 4 Way*. These contactors offer the best value for money that we have found, without cutting corners on the quality of components and they have a Full 3 year warranty.