Cat. GG-12-Collagen: 12 mm diameter, # 1 thickness, 90 pieces of CE certified crystal clear German glass coverslips with rat tail type I collagen coating on both sides for cell culture and confocal fluorescence microscopy, sealed 15 pieces per bag x 6 = 90, sterilized, ready to use. If this is your first time to order this 12mm collagen coated coverslips and want to test it for a specific cells, you can order this coverslip in half package H-12-collagen