The Penn Plax Crysta-Lux Clear Aquarium Lightbulb adds a dramatic color to your tank. The 6 inch light bulb has 25 watts of power, comes pre-tested, and is standard with 120 volts. The bulb has a non-rust aluminum base making it long lasting and safe for your pets. With light having many benefits for your aquarium plant’s life cycle, good light bulbs are important. That’s why Penn Plax has scientifically designed the fluorescent bulb as a safe, long lasting, and bright choice.