Why are there 4 sets of Vivera Retainers?

People often wonder why Vivera retainers come in a set of 4, 4 sets on for the upper teeth and 4 sets for the lower teeth. There are in fact 4 reasons why you're given multiple sets of them. Brought to you by Dr David Chen. 0:00 Intro 0:57 Last you a long time 1:37 Vs traditional retainers 2:25 Lose them 3:10 Just finished invisalign treatment 4:50 Summary recap