Microscope glassware for examination of blood, pond water, mold, and other minutiae. All of the microscope slides are optically clear glass 26mm x 76mm (about 1" x 3"), between 1mm and 1.2mm thick. The well slides, of course, have a concave well to hold a drop of liquid. Our each is a package of (12) well slides, or a box of (72) standard slides with ground or beveled edges. Cover glasses are the smaller and very thin pieces of glass used as the top of the glass slide sandwich. They are often used temporarily by simply dropping them onto a drop of liquid to flatten and spread it and to minimize evaporation. More confident microscopists will cement them in place to permanently preserve a specimen. Our each is a package of (100) cover glasses 18 mm square, #1 thickness (0.13mm to 0.17mm). If you need one, you need both.