Got this for a pair of Uvex Seismic safety glasses (for size reference). They're a nice tight fit on the earpieces just like I was hoping for. They could probably fit something slightly bigger before they just wouldn't go on.
You definitely don't have to worry about tearing them during "installation" though unless you've recently been exposed to gamma rays & turn green when you get angry - they're strong.
Also the adjusters slide nicely w/o coming out of adjustment on their own.

The companies customer service skills are even great - got an email from them shortly after ordering to make sure I had an easy way to contact them, should I need to for anything. I haven't, but I suspect that if I did, it would be handled just as professionally as they've already put themselves across. Just the impression that I got, but I guess I didn't expect an email like that for a reasonably low dollar item. Good to see that they care enough to do that though!

Retainer ends fit well over the ends of my sunglasses and seem very secure. The "slide" mechanism for tightening and loosening the retainer is snug but slides when you want it to. When tight, the retainer holds my sunglasses firmly to my head and when loose, I am able to move my sunglasses freely either down to my chest or off as I choose. I use this retainer on over the glasses sunglasses and the retainer still allows clearance over my regular glasses for easy removal or dropping on my chest. As far as durability, only time will tell - the retainer looks to be made of quality materials and I'm very happy with it.

This is a great design which brings my husband peace of mind! We recently bought him some Enchroma glasses (Ridge design). They are $350, so when we were planning a trip to an amusement park, we were nervous about him losing them. No sunglasses have ever come off of him in the past on these same rides, but the concern goes up when they are so expensive!

The first one we got was defective. One of the adjusters slid way too easily with practically no effort. However, the return process was a breeze, and I got my refund the day after it was shipped back. I just ordered another one right then, which is not defective and works great!

The quality seems really good, yet it's pretty affordable. The grips on the glasses are really secure! They don't slide at all! It takes just a bit of effort to get them in place, and once they are on, they stay on! My husband loves that they feel so secure (14" size) and that he can loosen the adjusters and let his glasses hang around his neck when we are not on rides and it's not sunny. Overall, very satisfied with this, and we will definitely buy more when/if these get worn down!

If you're interested in adjusting the retainer so its comfortable and firmly against your head, buy the 14". FYI, I have a big head and the 14"s are perfect for what I was looking for. They can be readjusted so you can take your glasses off without taking off the retainers. Additionally, I'm also pleasantly surprised that they blend in with my hair, so when I wear my black on black retainers you can hardly see them when worn.

I've only had these for a day, but I can tell I'll be wearing these a lot. Thus far, I'd consider them the best product on the market.

Pretty good product. My eyeglasses are older and have a thin frame. So the Pilotfish's foam end cap didn't hold the ear-piece tight. I ended up wrapping a small amount of duct tape around the ear-piece of the frame, then sliding the foam end cap over that. It's held on well so far.

One other thing: there was a small defect towards the end of the wire on one side of the strap which prevented the slider from going all the way to the end. Like the plastic coating the wire had been pinched and deformed. I made it work by filing down the pinched plastic bit.