Layla has one similar to this
Canadian Tire Therabed Heated Pet Bed Customer Ratings & Reviews - Top & Best Rated Products
except it is square- i relaly like that it has sides- whereas the one you were looking at is flat- i find if i put a blanket on the bed the sides almost wrap her up and i really like that- i find it really helps keep the heat in. she LOVES her bed- especially in the winter.
Also- the bed Lay has reacts to her body heat- if she isn't laying on it- heat isn't emitted- but as soon as she is on it- it starts to warm up.