Hi gang, Just got my flouride trays today. They fit fine, but are they supposed to be this flimsy? They don't seem like they will last through constant use. How long do they normally last?

04/21/17 Biopsy at ENT
04/25/17 Biopsy result SCC on left side tongue
04/27/17 CT Scans--shows shallow tumor
05/02/17 Pre-op
05/03/17 Surgery to remove tumor
05/08/17 Cancer still present
05/10/17 2nd surgery-
06/05/17 PET on 6th, RADS start on 06/20/17
07/11/17 Halfway point!
08/01/17 Last treatment
11/1/17 Cancer is back
11/15/17 Emory University surgery. neck dissection, left lymph nodes removed, tongue free flap from left arm with skin graft.