Replacement Bulb, UV-C, Bulb Length 5 1/2 in, Compatible Grainger Part Number 787CH3, Compatible Manufacturer Model Number Mfr. No. AC4700B, Mfr. No. AC4711W, Mfr. No. GG1000, Mfr. No. GG1100B, Mfr. No. GG1100W, Mfr. No. H5450, Number of Bulbs 1, Bulb Wattage 4 W, Bulb Rated Life 6 mo, Bulb Wavelength 254 nm, Germicidal Efficiency 99.97 Percent