I bought this for my 12lb small dog, and he loves it. We don't have typical windows, so the velcro was useless. I had to glue a piece of wood to the bottom of the bed to hook inside the window sill, and it worked great. The only thing I don't like about it, is the heater doesn't produce a lot of heat. I usually keep it unplugged, and my dog will still sit on it and look out of the window waiting for daddy to come home. 

Pros: easy to assemble, sturdy
Cons: heater doesn't get that hot