Product review (5 stars): A must have for DIY vent hoods
My husband is a novice wood worker who took on the challenge of building our own vent hood.  He bought this peice (which fit our appliance perfectly), then framed the base of the hood around it as a template.  It is a must if you are installing the vent we did as it will prolong the life of your hood by taking its fare share of the hot water and grease steam instead of a wooden base for a hood.

He highly recommends it.