This hollow glass prism is made from glass plates properly cemented together and measures 50 x 50 mm. It includes a stopper for sealing. The hollow interior allows the prism to be filled with different liquids or gases to change the refraction properties, making it a versatile tool for optical experimentation and the study of Snell's Law of Refraction. By varying the contents, students can observe how different media affect the bending of light.