Night Black Heat Incandescent Spot Bulbs. Emits a focused, 24-hour heat source ideal for reptile basking areas Great for night-time viewing to observe natural nocturnal behaviors Ideal for tropical and desert habitats; the bulb provides focused heat while the photons emitted by the filament never escape the dark tint. The spot bulb provides a focused beam of energy to heat the air inside the enclosure to create the warmth needed for a healthy reptile environment. The bulb is made from glass containing rare earth black phosphors, which simulates the moon’s natural glow for nocturnal viewing without disturbing the reptile’s day/night cycle.