Ecotronic TS35E T8 to T5 Fitting conversion allows T8 lamps fittings to be converted to the corresponding T5 lamp with the energy saving benefits. But this technology has been overtaken by LED technology where it is easier and cheper generally to convert T8 to LED and the energy savings are greater. See our energy saving LED T8 lamp search NLT82040 19W ref (2501001536)