Cat. GG-25-1.5-Collagen: 25mm diameter, # 1.5 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. You can order H-25-1.5-collagen if you want to do a testing culture.