LR2 lenses are specially designed for Luxeon Rebel series of LEDs. Special care was taken to make a uniform white or warm white illumination.Th lens material is an optical grade PMMA which allows use of high current and temperature conditions (105°C/220°F). LR2 lenses offer the best available optical efficiency, more than 90%, with an extremely good cut-off of light. The lenses come with position pins. Fasten to PCB with appropriate adhesive tape, please check fastening details from this link: (http://www.ledil.com/datasheets/DataSheet_TAPE.pdf)