Powersun is a Mercury Vapor bulb. They are typically only used on free range cages. It is a 2 in 1 bulb. The issue with these and chameleons is you have to have a solarmeter to dial in the UVI level at the branch. But the reason we do not use them on cages is the UVI output is very high and the heat is much too high. To get the right UVI and the right temp does not work well with cham species because of their 3 UVI an 80-85 basking range. In a cage this is very difficult. On a free range it can be done but you still need a solarmeter to know your UVI.