Features： 1、SPECIFICATIONS: Double sided right angle optical prism, the prism constant is -25mm, effective diameter is 25.4mm, accurate and stable. 2、OPTICAL GLASS: This double side prism uses optical glass, with fine cutting and polishing to ensure accurate measurement. 3、GOOD REFLECTION: coating enhances the prism reflective ability, making it clear and bright, improving measurement accuracy. 4、PLASTIC HOUSING: Oxidized plastic coated lens, which ensures good wear and impact resistance, greatly extending prism lens service life. 5、L SHAPE STAND: The right angle prism has L shape stand for stable operation, widely used for railway, tunnel and highway detection. Specification： Item Type: Right Angle Prism Material: Optical Glass, ABS Color: Black Constant: -25mm Effective Diameter: Approx. 25.4mm / 1in Application: For tunnels, railways, mines, highways, dams, steep slopes detection, etc. Package List： 1 x Right Angle Prism