T12, 1 1/2 inches (38mm)
PHILIPS 100-watt, 6-foot “Long Length” High-Output Internal-Reflector UVA-1
This 6-foot UVA-1 bulb is “F71″ length and measures 70.25” far-end to far-end. Includes an internal reflector (the “R” in the part number) to increase UVA-1 irradiance. Can be made to fit a SolRx 1000‑Series device.