Manufacturer's part #06 LGD 415. Original price: $131. This is 2.0mm diameter by 10.69mm long with a design index of 1.592 and a numerical aperture of .46. Acceptance angle is 55 degrees and fractional pitch is .50. These are well suited to coupling the output of a diode laser into an optical fiber. Easily achievable aberration correction without complex multielement systems or aspherics. Reflection is reduced to less than 1.5% per surface with the Broadband AR coating. Gradient index lenses (GRIN) are made from Selfoc, a radial gradient-index material. These can transfer collimated light from one end of the lens to the other. Also, can transfer an inverted real image from one end to the other. Unused. This is actually so small it comes in a pill capsule!