Feature: 100% Brand New and high quality Our Professional Grade Glass Cover Slips are square and manufactured from high quality glass. Non-fogging, non-sticking and no bubbles, scratches or striations. The slides are pre-cleaned, flat, and optically clear. Superb flatness uniform distortion-free surface. Specifications: Size you can choice : 18mmx18mm Thickness: 0.006" (0.13 - 0.17 mm) Material: Glass