This lamp is 100% compatible with the Lennox Y0390 OEM lamp selling at a much higher price, but not made by Lennox. It measures 410mm (about 16.1 inches) excluding the 4 pins on the end of the lamp. The base has a raised ring to help with installation. Its peak output is at 254nm (UV-C) for use in Lennox air purification systems. The rated useful life is 10,000 hours.

The lamp is used in these and other air cleaning and purification systems:
Lennox Healthy Climate UVC24C
Lennox Healthy Climate UVC-24C