How to Measure a Prevent© Bonnet Filter
Prevent washable bonnet filters are available in 4 different styles. They are available in either black or white electrostatic polypropylene media, finished with an elastic edge. Made to fit any fan guard, ventilation exhaust opening, or air intake opening, the bonnets are manufactured to the EXACT size ordered, so measure carefully. Filters are not returnable.
Model BONNET When measuring for fit over a fan guard grill, measure up and over the front half of the grill:
For price, round this measurement up to the next whole number and convert to sq inches.
Model FANGUARD Measure for BONNET, as shown above. In addition, measure the motor diameter for the center cutout.