Emits UVB a full 20"/51cm from the surface of the lamp to prevent or reverse Metabolic Bone Disease. (Compared to 12"/30cm on the ReptiSun® 5.0). Optimal for use with larger terrariums where greater than 12" of UVB penetration is needed. The ReptiSun® 10.0 is also recommended for use above screen covers which can filter out up to 50% of the UVB wavelengths.