I wear a 10 1/2 shoe and boot. I ordered the XL Workbrute - my gym shoes slip right in, even when I'm wearing them. There's about 1" of space in front of the toe.  Boots - I had to force the boot in before putting it on (took some work) - after the boot was in place, I rolled down the top to expose the laces, etc.  I slipped my foot it, laced up the boot, then rolled up the PVC over-boot. There was about 1/2" of open space in front of the boot.

There was no was a smaller boot would have fit over the boots. Tried it with my Browning hiking boots and my work boots.