This cold mirror is designed to operate at a 45 degree angle of incidence. It reflects the visible spectrum and transmits the heat (infrared). The average reflectance is greater than 95% from 425-650nm.Transmittance is more than 85% average from 800-1200nm.These filters are commonly coated for normal incidence applications as well (see CM0-VS.-STD) Custom angles of incidence can be designed to specification.