thought it was in 2 parts but its in one for both top and bottom. like a mouth guard. Ive only worn it twice for an hour so can't really say if its worked for straightening. I have a couple of teeth that have started to slightly over lap on the bottom. used to have a brace when younger so I thought this may work as its only minimal. it has made them ache like would if had a brace a little. so will see how it goes.
The quality is poor the smell is strong . It is not effective