Honestly? Shocked but extremely happy that I trusted the weird Instagram ads... I was skeptical about how they claim my retainers would be shiny and clean after one use, and I am not disappointed! I used the free tabs that came with the device and my retainers were clear and clean - they looked better than they did when they were new?! It is sooo convenient to throw them in while I shower and have them do their own cleaning cycle instead of me brushing like I had done for years (I had Invisalign and now have my retainers). I seriously wish I had this baby when I was brushing every time I ate. I like using the longer cycle and I'll throw it on and hop in the shower at night before I brush my teeth. It's done in 5 minutes and they come out good-as-new. I love the Onyx black as it goes better with my bathroom. Thanks for the ease, Sonic!