This EKSMA Optics mirror is a protected silver plano-convex spherical mirror, designed with a base shape of a circle and a diameter of 25.4 mm. The mirror's thickness at the center is 6 mm, and it has a focal length (EFL) of 500 mm. The mirror's front surface is coated with EKS 0025protsil 4000, a protected silver coating, optimized for a wavelength of 400 nm. The mirror's curvature is defined by a radius (R1) of 1000 mm, making it a convex mirror. The mirror is made of N-BK7 Schott, a popular optical glass known for its excellent optical properties. According to the vendor's website, this item is currently in stock.