UK Card Crafts Clear A4 Acetate sheets are just great for aperture windows, OHP – in fact, its uses are numerous to mention. Acetate Sheets are just great. Acid free. This acetate is very clear and thicker than normal acetate. A4 QTY – X 5 Acetate sheets per pack. 240 Micron – Thats Thick, Normal acetate is 140 micron.