Filter is made of optical glass with a multilayer antireflective coating on both sides. Filter eliminates up to 99 percent of glare for a clear sharp image. Conductive coating blocks 99.9 percent ELF/VLF E-field radiation. In addition, 99 percent of static electricity gets dissipated through a grounding cord. Adjustable brackets position filters for easy viewing. Filter fits 19" to 21" CRT screens.