Nowadays the preferred phototherapy treatment for skin diseases like psoriasis is done through the use of the ‘B’ bandwidth of the UV spectrum (290 to 315 nm), since this requires no photo-sensitizing agent. But some patients do not respond to UVB treatment, and for them, phototherapy systems containing UV lamps with an ‘A’ bandwidth of the UV spectrum are used. These lamps have a wavelength of between 315 to 380 nm.Phillips offers highly reliable T12, PL-S and PL-L lamps emitting this spectral wavelength bandwidth.N.B.: Our UVB lamps are NOT registered with FDA as medical devices as they are NOT packaged or labeled for commercial distribution for health-related purposes. US customers are referred to the UVB and UVA lamp range brochure US version.