One other thing , I wrote OMtech ask them the size of their 40 watt tube , they told me it was 700 mm 50 mm Dia. This is not a true 40 watt tube. They mislead you, yes it puts out 40 watts but not a steady 40 watts, its a burst and then drops down to under 30 watts doing the actual work. A true 40 watt tube is 1010 mm long 50 to 55 mm dia