I have used both retail kits and bought on line. They both work. I am familiar with At Home and the extra you get with it is that you can send in your sample and they will run a gc/ms on it and you will get an exact amount of thc metabolites in your urine in ng/ml. The catch is you have to fail the test, if you are under 50 ng/ml then they will just report that you are negative for thc.