Rectangular Coverslip Cover Glasses measure 24x40mm with a thickness of #1 (0.13-0.17mm). Manufactured from clear, pure white borosilicate glass for excellent clarity, flatness, and chemical resistance. They conform with ISO 8255 standard for dimensional tolerances, thickness and optical properties, and are free of flaws and blisters. Pack of 100 coverslips comes in a plastic storage box with hinged lid for protection.