This was purchased for my 11 year old for Lacrosse after trying and failing at molding two traditional boil and fit mouth gaurds. From past experience with martial arts we know he's a chewer, so we wanted something that was a durable but comfortable.Over all the fit is good, it seemed a little small out of the package, but we followed the microwave instructions and once fitted the size was perfect.So why four stars? the strap, it's heavy duty and fully attached, exactly what we wanted, however it is not adjustable, it has one slot to feed the end through. Since it's fairly rigid attaching it to the mask of our son's helmet it was awkward and pushed on his teeth. After bending and moving it around several times we forced it to wrap around a bar so it rest in a better position for him to use.Overall good product, he's been using it for about two months, it has a little wear from his teeth, but still holding up well.