One kit provides 3 kinds of different coating substrates for your culture testing, optimization, or  trouble-shooting of culture problems.  Total 45 pieces of coated German coverslips, 12mm diameter #1 thickness, 15 pieces for each coating substrate x 3 different kind substrates. Sterile, ready to use. Note: The coating substrate is identical in all different diameters and thickness so you can choose different diameters and thickness of your choice after the testing.