the retainers dont last and the price increase above what a replacement of the last set would have cost had I lost or damaged them ($99) seems ridiculous - be prepared to spend another $1000 a year to maintain. And then the time it takes to get the retainers - if you dont had a spare pair and they get damaged your teeth wont maintain shape in time for the next lot. Minimum 21 day wait - but at the moment they say longer - but not how much longer. The retainers stretch so when you get a new set it's a few days of very tight retainers to get your teeth back to perfect. Each time feels like a gamble.