This Wrench is designed to work with Boshart Big Blue Housings for both 4.5" x 10" and 4.5" x 20" filter length. The housing dimensions are much different than filter dimensions, this wrench has an inner diameter of 6 1/4" and 5 7/8" at the nubs. So where the wrench would come snug on the outside of the housing would be slightly less than 6".