I received a refund on my order regarding the missing lamp, and put my 36w Sylvania to use. It's nice and bright, but the hertz flicker is a bit stronger with that lamp. This is a HPF magnetic R.S ballast for two PL-L 40w lamps... the hertz flicker is exactly like that of most F40T12 HPF R.S magnetic ballasts. With the Sylvania Eco Dulux 36w lamp in series with one Philips PL-L 36w lamp, the hertz flicker looks almost the same as if I were to install a 34w lamp in series with a 40w lamp. It's tough to explain.