The covers fit a pair of Mavic Ksyrium cycling shoes just fine and keep my toes warm at 45deg F. The only issue I've had with these is that it's only been about two months(20 rides) and one of the straps is starting to rip. Durability is very questionable right now, but we'll see.
Overall great purchase (especially if you can snag these on sale).
I bought thermal toe cover to replace a standard pair that were wearing out. My main issue is that the rear opening has a velcro closure that is held together by an elastic band. This made it hard for me to get the toe cover over the bottom of the MTB shoes I use. I ended up cutting the elastic band off the cover. Unfortunately, the velcro closures are not that long, and one of the toe covers fell off while I was riding. A friend saw it falling and picked it up. I ended up sewing some velcro that I had laying around to lengthen the closure. These may be better suited for road shoes, where there are no lugs on the soles that make it hard to install the cover.
I had the older version of these booties which I really liked but they wore out. I liked the older style better but these are a little easier to put on and and a little easier to get to the middle velcro strap on my shoes.
I purchased this product to wear over my bike sandals. The sandals have adjustable straps that allow me to layer socks for winter riding. This product is flexible enough to fit over the expanded sandal and block air flow. I am riding in temperatures as low as 25 degrees and staying dry and warm.