AixiZ Red Laser Glass Lens with multi-coating, great penetration rate for red lasers in the 635 to 650nm rance, 9mm in diameter for AixiZ 12mm laser module housing. 9mm Glass Lens for 600nm+ , 650+IR nm AR coating, M9 * P0.5 thread, length 10mm Lens Specifications EFL: (effective focal length) 8.3 SD: (diode to the lens distance) 5.3 CA: (effective aperture) ¢ 5 M: (thread diameter) M9 * 0.5