Durgol is highly effective, easy and safe to use and is guaranteed to decalcify quickly and easily without the need to wait for the decalcification process to work. Regular use of this special formula will ensure the optimal quality of your espresso and extend the life span of your machine. Durgol swiss espresso leaves no residue and after decalcification and rinsing, your machine is completely safe for use. 4.2 oz. per bottle.