I live in Arizona but it does get cold here in the northern part of the state. I've used a couple of different booties and my feet have always gotten uncomfortably cold/frozen on those morning rides when the mercury gets south of 40 degrees. I decided to take a chance on these shoe covers and save the 120+ dollars compared to the price of dedicated winter shoes.I have used these on two rides so far. Both with temperatures in the low 20s. One ride was almost four hours, the other was 1.5. The long ride was primarily slow speed riding on very technical terrain with some hike-a-bike and go back and try it again "sessions". So while the temperature was low (16 degrees and snowing at the start) there was little issue with wind and lots of opportunities to get the blood in the feet flowing by walking. My feet stayed comfortably warm the entire time. The 2nd ride was more cross country - fast (more windchill) and on the bike the entire time. On that ride my feet did get chilly by the end, but were NOWHERE near the uncomfortable blocks of ice they usually become. My feet were warmer at 20 degrees than they had ever been at much higher temps with other booties.A size large slid very easily over my size 43 mtb shoes. Secures with velcro instead of a zipper. The high ankle provides okay coverage if you splash through a water crossing, but are not sealed at the top in any way. Seem durable - granite boulders tried to rip them a few times with no luck. Any cover feels bulky to some extent, but these are light and I didn't give them another thought after a few pedal revolutions. There is a little strap at the front that hooks under the shoe to help keep the cover down over your toes.I'm glad I found these for $80, but would buy again at full retail price if I needed to. Recommended. Particularly if your really cold season is short and not too brutal. Why spend $200+ on winter shoes when you can get these?According to the manufacturer an XL should work with my size 46 MTB shoes. I ordered XXL "just in case" and even they seem small, especially around the ankles. Other than that, I like the design and the fact they open completely down the back, much easier to put on than my old shoe covers. I also like that none of the shoe cover is dragging the ground, it wraps around the spikes of the shoes instead. They seem plenty warm, especially with an extra set of toe covers.Always order a size larger then you think you need! Originally ordered a smaller size and they didn't quite fit - too snug. Larger size allows for a much better fit.These were large when I normally wear medium. The still were tight. Size up one or two sizes.I put a pair of toe warmers on my socks, then I cover my warm-weather cycling shoes with these, and cold feet is simply not a problem anymore (as low as 22°F). These covers are solid and rugged. The two-stage Velcro attachment makes it easy to put them on and get them snug.GREAT