For Hole Sizes from 7-7/8” clear up thru 58”, our Hole Opener is built with replaceable Arms as well as replaceable Cutters. This feature allows each size body to be converted to more than one hole size by changing out the Arms & Cutters. This style of Hole Opener is called the RHO Series. Hole Sizes from 7-7/8” up thru 36” have 3 Cutters & 3 Arms per assembly. The larger size, starting with 42” can have either 4 or 5 Cutters & Arms per assembly depending on the Body size. The RHO Series Body & Parts are not interchangeable with other brands of Hole Openers.