This is a 4ft 40w T12 Triphosphor Fluorescent tube in a 3500k / standard white colour, used within T12 batten fittings, these tubes are ideal for lighting large areas such as warehouses and factories, but can also be used in domestic environments. F40W/35, as they are commonly known, are a traditional T12 type of fluorescent tube with a G13 cap type and are roughly 38mm in diameter. This particular tube is extremely rare due to all major manufacturers making them obsolete in 2012. This tube is Triphoshor meaning they will last much longer and has around a 20% better light output than the older halophosphate tubes. The Triphosphor T12 tubes have been introduced to allow customers to replace their old T12 tubes with higher quality and longer life tube over the original (15,000 hours vs 8,000 hours). The benefits are maintaining the same look for old fittings while using modern T8 type technology. These tubes have been made obsolete due to energy efficiency. Feel free to call us to find how you can upgrade to LED options today. 01138876270