For more complex tooth movements, elastics are indicated. I tried a few different ways of putting on these stretchy bands. You fit them around the little cut outs on both aligners. Trying to put them on after the aligners are in just did not work well for me. What worked for me in just 10 seconds, was to put the elastics on the aligners outside of the mouth and then carry the aligners into the mouth. Quick, easy, and efficient ?