Penta Angle Prism BK7 K9 is an optical prism made from BK7 or K9 optical glass, designed to deviate light by a fixed 90-degree angle while maintaining image orientation. Unlike standard prisms, the penta prism provides stable angular deviation regardless of small alignment errors, making it highly valuable in surveying instruments, optical measurement devices, and imaging systems. BK7 and K9 materials ensure high optical clarity, low dispersion, and excellent transmission in visible wavelengths. These prisms are precision polished to achieve high surface quality and angular accuracy, making them suitable for professional optical systems requiring stable beam direction control.