Secures to front of Tweak head. MR16/PAR16 size holds one lens or louver; PAR20, PAR30 and PAR38 sizes hold up to two lenses or louvers (sold separately). Lamps not included. LineVoltage PAR16 GU10 lamp up to 50 watts. LineVoltage CMH MR16 lamp up to 39 watts. LineVoltage PAR20 lamp up to 50 watts. LineVoltage CMH PAR20 lamp up to 39 watts. LineVoltage PAR30 lamp up to 75 watts. LineVoltage CMH PAR30 Long lamp up to 70 watts. LineVoltage PAR38 lamp up to 120 watts.