Product review (5 stars): Muck Boots best accessory!
I bought two of these on Ebay before they became available on Amazon (for less).  My daughter wears mid height muck boots in her classes learning to be a veterinarian.  The bag is FANTASTIC!  Easy to drop the boots into, easy to clean (just hose it out and hang it upside down to dry.  I give it a good squirt down with the same dilute bleach solution that I use on her boots.

When you're in a hurry, you just have to have someplace to plunk your boots till you can clean them off.  This is easy to carry, waterproof, and amazingly light weight.