The Zilla 4 Pack of Reptile Terrarium Heat Lamp Bulbs are perfect for warming your reptiles in tropical or desert environments. These bulbs have heavy-duty filaments that yield hours of performance, and they’re made from glass that contains rare earth black phosphors, which simulate the moon’s natural glow for nocturnal viewing. The bulbs provide ambient heat in which the photons emitted by the filament never escape the dark tint, heating the air inside the enclosure to create the warmth needed for a healthy reptile environment.