Single, prepared microscope slide with three crossing threads. The layered red, yellow, and blue threads are ideal for elementary and middle school introductory lessons in microscopy. It provides students with a simple tool for learning microscope properties and examination techniques, including depth of field. Protective cardboard casing. The slide measures 75mm (3") wide, 25mm (1") long and 0.06" in height. Slides are expertly prepared and labeled for easy identification. All materials in Eisco Labs slides are completely inert and sealed in glass.