Drink plenty of apple juice for at least three days (a week is better) before your first flush. The juice will help soften the stones. When you do the flush, be sure and take the Epson salt drinks, DO NOT SUBSTITUTE !, the chemicals in Epsom Salt relax the bile ducts so stones pass much easier. My largest stone was 2.6 cm in length, I've had several 1.5-2 cm, all passed painlessly.