Lotus Connect Store › Eisco Labs Glass Semicircular Block, 3 1/2"x15/16" (100x18mm) Eisco Labs Glass Semicircular Block, 3 1/2"x15/16" (100x18mm) $8.36 All faces fully polishedclear glassWorks well in ray box experiments (Eisco Labs part number PH0602A)works well with low power monochromatic light source100x18mm glass semicircular block for light refraction and geometrical optics experiments Quantity: Add To Cart Added! All faces fully polishedclear glassWorks well in ray box experiments (Eisco Labs part number PH0602A)works well with low power monochromatic light source100x18mm glass semicircular block for light refraction and geometrical optics experiments