Reptile Systems Zone 3 T8 600mm (24″) 18W is best used with a Fluorescent controller, and with a Reflector to double the light output. For the maximun enjoyment of your terrarium/vivarium we recommend that you replace your quality Reptile Systems lamp at least once a year. Extra high output 10% UVB for the synthesis of vitamin D3. Full spectrum lamp. Produces excellent natural colours.