Cat. number: GG-24-Collagen: 24mm 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. H-24-collagen is the same as GG-24-collagen and is half packing size for new users to do a testing culture.