This product is a 5 mm diameter, 1 mm thick Flat Window made from Sapphire, a material with the ID al2o3 mal-1972-n-o. Sapphire, known for its exceptional hardness and chemical resistance, is an ideal material for protective windows. The window is coated with an AR coating on both the front and back surfaces, specifically the edm nir-i std curve, which is designed for the Near-Infrared (NIR) I region, covering the wavelength range of 600-1050nm. This coating enhances the window's performance by reducing reflection and increasing transmission in the specified wavelength range. The window is shaped as a Thin Lens, and it is sourced from the reputable vendor, Edmund Optics. According to the vendor's information, the product is currently in stock and available for immediate purchase.