Most manufacturers are pretty good at finding filters that are some odd size, not available at your local hardware store. They can make more money on parts that way.

An air filter unit is easy to make with a furnace fan out of your local HVAC shop boneyard. A plywood box and some filters, and youre in for about $20.00.

Visit the WOOD magazine D-group on dust control for a pile of good information on DC and air filtration. They have a nice tools D-group too.

: They also have the replacement filters on closeout. It takes an exterior and
: interior filter. Sold separately of course. Most likely, the exterior
: filter can be interchanged with any filter of the same size, but the
: interior filter is bag like. A pair of interior filters are on closeout
: for $19. Normally, it is $47.

: Kurt