Cardboard Tray Mailer & Wallets provided by STE-Mart are made of heavy dusty cardboard. They can accommodate both the CITOTEST® standard microscope slides in dimensions of 75.0mm×25.0mm with thickness from 0.8mm to 1.2mm and also the microscope slides of 76.0mm×26.0mm×(0.8-1.2)mm on the market.