Round cover glasses 13mm diameter. Box of 100 or case of 10×100 available. Other sizes available are 10mm,15mm,18mm or 20mm for the same price. This brand of cover glass is made of colorless borosilicate glass (D 263) with an optimum hydrolytic resistance HGB1. Our coverglass is manufactured in accordance with the international standard ISO 8255/1 and is ready to use. In order to prevent sticking, caused by stacking flat coverglass, we use very fine glass particles to powder the surfaces.