I saw this review from January 2105 on Amazon, which offers replacement headbands for $45.49 and free shipping (today). I called the number and a man asked for my name and address and said he'd send one to replace mine, which broke about a month ago.
"ASTHE OTHER REVIEWS STATE THIS HEAD BAND IS TOO CHEAP AND FLIMSY TOSUPPORT THE WEIGHT OF THE SHIELD.I WENT TO USE IT THE OTHER DAY ANDFOUND IT WOULD NOT TIGHTEN UP LOOKED INSIDE AND SAW THE PLASTIC BANDHAD BROKE.THE SHIELD ITSELF IS A 5 STAR WITH A 1 STAR HEAD BAND,THISNEEDS FIXING TREND.BASED ON THAT UNLESS YOU WANT TO SPEND 40 BUCKSEVERY FEW TIMES YOU USE IT I WOULD NOT RECOMMEND AT THIS TIME.FIX THEPROBLEM TREND.
update
afterwriting this i also wrote to the distributor for trend air shields.igot a response back within hours telling me to call trend directly at877-918-7363.he said they knew of the problem are are willing toreplace the band at no charge.and supposedly this problem has beencorrected."