Dichroic filters are durable glass color filters that transmit only certain wavelengths of light, reflecting the rest of the spectrum, rather than absorbing it. Since virtually no energy is absorbed by the filter, light transmission is significantly higher than traditional gels and will never burn out or fade. Our Dichroics are available in many standard sizes or can be custom cut in any size up to 13.5" in diameter. The material is durable borafloat glass with 1.75mm (.069") thickness. They are also available 1.1mm and 3.3mm thick.