Acrylic Block Semicircular Block, Acrylic - Polished Sides - For Use In Light Light Refraction Experiment DURABLE - Ideal teaching tool for science lab work Block, Acrylic Semi-Circular 60 Mm (Diameter) X 15 Mm Thickness ... Semicircular acrylic block, 90mm diameter, 12mm thickness. Add to Cart. $8.80 RAY BOX READY - Works well with these type experiments as well as a low power monochromatic light source EISCO Rectangular Refraction Block, 3 (75mm) x 2 (50mm) x 0.5 (12mm) - Optically Worked Glass - Slightly Beveled Edges - Excellent for Physics Experiments... 90 MM x 16 MM BLOCK - Imperial measurement of 3-1/2 x 9/16 Semi Circular Block - Acrylic - Eisco Labs OPTICS - Can be used for light refraction and geometrical optical experiments