This is a 55 Watt 22 1/4 inch 4-Pin Power Compact UV sterilizer bulb. Never look at the bulb when lit - ultraviolet light is invisible to the human eye, but should never be looked at directly as it can be harmful.Ultraviolet light is part of the electromagnetic spectrum that lies beyond the purple range of the visible spectrum. The Uv spectrum is further divided into wavelength ranges named Uva, Uvb, and Uvc. Uva (Sun Tanning, Testing, Inspection, Insect Traps, Stage Effects, Blacklight, Phototherapy* (315-400Nm)) Uvb (Sun Burning, Inspection, Analysis, Testing, Phototherapy* (280-360Nm)) Uvc (Germicidal (253.7Nm), Ozone Producing (185Nm)). Specifically, Uv-C light causes damage to the nucleic acid of microorganisms by forming covalent bonds between certain adjacent bases in the Dna. The formation of such bonds prevent the Dna from being unzipped for replication, and the organism is unable to reproduce. In fact, when the organism tries to replicate, it dies.