Metric Rectangular Optic Mounts have a bar-type design with non-marring mounting surfaces, making it ideal for rectangular optics such as filters and mirrors, as well as cylindrical lenses. The mounts are available in 25 or 60mm sq for rectangular or square optics. They are compatible with a M6 x 1.0 mounting thread. Metric Rectangular Optic Mounts are constructed of black anodized aluminum with a stainless-steel post. Posts and Post Holders are required for mounting to a breadboard.