Probably Barz Optics most best “floating” sunglass retainer - with the most buoyancy. It has an adjustable toggle to assist in keeping the glasses on your head.It has 2 black rubberised tubes on each end which will suck onto most sunglass temples (except really wide ones).
It will have no issues with polycarbonate, TAC or CR39 lenses glasses and should float even sunglasses with glasses lenses.However, advisable testing them in still water before you venture out into deep water.
Barz Optics is an Australian based family company located at Burleigh Heads in Queensland on the east coast of Australia. The Company was established in 1996 by Kevin Barr - a former surfing champion with 45+ years experience in the surf, snow ski, jetski, sailing and sailboard industries.