A 175w mv bulb would be used for a room size enclosure. Its not needed for typical tegu enclosure. The 175 is meant to be put high up to reach lond distance in a typical enclosure it would be too hot and a waste of electric and uv. With a 100watt spot it has to be a min distance of 18 inches away from the animal wich would work fine in a normal enclosure also you can use a flood. Make sure to check your temps the flood doesnt get as hot as the spot on a concentrated area it disperses the heat these bulbs are also much more expensive than typical bulbs you also dont get the brightness of having a flourescent becouse the light is concentrated in one area