SATCO's Type B ballast bypass lamps, designed to replace T8 or T12 medium bi-pin fluorescent lamps are available in 2', 3', and 4' lengths. They are engineered for single or double-ended wiring options and will not light unless ballast is bypassed. Commercial venues, schools, hospitality, health care - any large scale lighting application - will benefit from immediate energy savings and less maintenance. Sold as a 25-Pack