The United Scientific RCB115-G rectangular glass block is suitable for use in science experiments involving refraction physics. The block is made of polished glass for optical clarity and measures 115 x 65 x 20mm (L x W x T, where W is the horizontal distance from left to right, L is the horizontal distance from front to back, T is the thickness from top to bottom).United Scientific Supplies manufactures laboratory supplies and science education products. The company, founded in 1992, is headquartered in Waukegan, IL.