I’ve had it for about 7 days. My retainer is worn 24/7 and I also smoke so I stain it often and it’s got so much yellow build up in small places. It said to give it time to work. And they were right. I do see a difference in my retainer , I’ve been brushing it with soap before hand and washing it off thoroughly because it’s so gross, and putting it in there for two cycles on one tablet. I read the instructions and I wait 10-20 mins before another cycle, usually before my shower and after at night and once in the morning. 7 days consecutively, I’d give it a 6 out of 10 so far. In going to continue but it seems very promising and I love the UV oral appliance too, it takes the same C charger as my phone and it makes my retainer more clear actually and I love it. Bundle was worth it.