While that title may not instill confidence in possible purchasers let me do my best Kevin Hart and "Let me explain".
These are toe covers, they are not boot covers, they are not heated wool socks, they are not leg warmers. If you think these things will save you from 10deg weather they will not.
These protectors will save you from wind chill, some wet weather/snow but they cover the tops of the shoes mostly and if you have holes on the bottom, well try something else.
These things are a boon in the 30-50deg range especially if it's windy. I like them and they are easy to mount, then leave on all Autumn/winter. These are cheap to try even if they don't sit your taste it's not a big gamble.
I'd been searching and searching for a toe cover that would work with my man bike shoes. Thank goodness I found this pair of toe covers! They don't interfere with the front lugs so it's easy to walk those hike-a-bike sections of the trail. Toes stay nice and cozy on the cool winter days.
So far I've used these on several rides that started in the upper 30's and warmed to the mid 50's with no problems. They seem like they may be good down to the low to mid 30's. I use Sidi mountain bike shoes with velcro closures with Speedplay Frog pedals on my road bikes and it is not easy fitting them on the shoes so I plan to leave them on one pair of shoes until spring.