EPCO’s T5HD Series Tube Guard’s larger diameter and “vented” end caps allow a layer of air to act as an insulator to absorb heat from the T5HO lamp and cool it before making contact with the inside wall of the tube guard. The vented end caps allow the release of heat, further reducing the temperature build-up inside the tube at a critical position of the T5HO lamp. The larger diameter accommodates heat sink screens that control and distribute the heat, lowering the temperature over a larger area at the end of the tube guard. All of these things result in a 25-degree Fahrenheit temperature reduction compared with other similar products. In addition, EPCO recommends the use of heat sink screens with all of its tube guards, to aid in controlling heat that is generated by the fluorescent lamp. Engineered Products Co.