The Hi-Tech Lamps part number F21T5/841-U is a 21 watt (21W) fluorescent tube lamp made by Ushio. This lamp has maximum overall length of 863mm (34in). This lamp has an average lifetime of 20000 hours. It produces a color temperature of 4100 Kelvin (4100K) with a color rendering index (CRI) of 85 and an initial output of 2100 lumens. This lamp is also known as Ushio F21T5/841 and 3000381.