If you want an alternative, something like this https://www.amazon.com/gp/product/B002P9WPO8 works for me to about 10° which surprised me because I always got cold toes. I've found also that just a thin plastic bag underneath it makes it considerably warmer, though doing that I sometimes need to change socks afterwards.

This morning I was asked if I planned on riding in Friday. Uh sure, why? Well, he said, it's supposed to get really cold and lots of wind ... checking the forecast, about 26° and breezy It's been amazingly mild so far this winter.