I used XXXtra Clean once for a pre employment and it worked like a charm. Get the big bottle, like $50, and don't eat any fatty foods for 24hrs prior. Drink this bottle, a bottle of water, piss 3 times, and drive to the clinic. Leaves you clean for about a 4 - 6 hour window. Product flushes all of the cannabanoid metabolites that are currently in the bladder, and when you go, the ph is correct and the creatine levels so dilution isn't detected.