Cat. H-12-1.5-Collagen: 12 mm diameter, # 1.5 thickness, 45 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 3 = 45, sterilized, ready to use, fit into 24 well plates, most popular for confocal imaging, You can further reduce the cost by order bigger package of this collagen coated coverslips, GG-12-1.5-collagen, which has 90 pieces in a package