Dennerle trocal t5 special plant amazon day have a diameter of only 16 mm the t5 amazon fluorescent tubes offer higher light intensity than comparable t8 tubes and are optimized for operation at an ambient temperature of 35c a unique advantage of the new t5 fluorescent tube technology from dennerle is the uv stop feature similarly to the previous t8 models all the new tubes possess a special uv stop protective foil which completely filters out uv light under 400 nm a wavelength range pa