make sure it has vitamin B...and creatin (sp?)
the vitamin will add color, the creatin is a protien that is sometimes scanned for.

I have used various producs as I just described a total of 3 times but do not recall brands. I smoke daily for the past 20yrs. The three times I tested, I stopped smoking 10, 8, and 2 days prior to test. I passed everytime.

Follow directions exactly. Dont over do it with water - you may come up 'dilute' and need a re-test...this may look quite suspicious.

good luck