These are 50pc pre-cleaned blank microscope slides with 100pc round cover slips. The dimensions of the slide are 1" x 3" (25mm x 75mm) with ground edges. The cover slips are 3/4" (18mm) in diameter and 0.006" (0.15mm) in thickness. They are brand new in factory-sealed box. Features & Specifications: Quantity: 50 blank slides and 100 round coverslips. Dimensions of Slide: 1" x 3" (25.4x76.2mm). Dimensions of Cover Slips: 3/4" (18mm in diameter) x 0.006" (0.15mm in thickness). Material: optical glass. Unbeatable Low Price. Satisfaction Guaranteed or Your Money Back!