01T8 or T5
The number after the T is the tube diameter in eighths of an inch: a T8 is about 26 mm across and a T5 about 16 mm. They use different holders, so check the old tube before ordering. Bring it in or send a photo of the printed code on the glass.

T8 tubes are 26 mm across; T5 tubes are 16 mm. They are not interchangeable.








