Square glass cover slips measuring 18 x 18mm (0.13 - 0.16mm thickness).Allows the user to cover their microscope slide samples which can also protect the objective lens of the microscope against any unwanted transfer from the sample being observed. Students should be warned of their delicate nature.Box of 100 cover glassesSquare: 18mm x 18mmThickness: 0.13mm - 0.16mm