This is the 05D620ER.1, a 12.7 mm diameter Borofloat Economy Broadband Metallic Mirror with a thickness of 3.1mm. This mirror is sourced from the reputable vendor MKS/Newport, and it boasts an Enhanced Aluminum coating optimized for the wavelength range of 450-700nm.
The mirror's base shape is circular, making it a versatile option for various optical applications. The material ID, borofloat33, indicates that it is made of Borofloat, a low-thermal-expansion glass commonly used in precision optics due to its excellent optical and mechanical properties.
The coating on the front surface is New ER.1, which is known for its high reflectivity and durability. The mirror's shape is thin lens, further enhancing its functionality in optical systems. The mirror's web links are valid and indicate that it is currently in stock, making it readily available for your optical needs.