Abstract: An adjustable adaptor for fitting about various diameters of shafts thereby eliminating the need for various sized adaptors. The inventive device includes a first adaptor portion and a second adaptor portion that are adjustably connectable with one another forming an adjustable adaptor for fitting about various diameter shafts such as an axle shaft of vehicle. The first adaptor portion has a first brace member and a plurality of staggered first ribs extending from the first brace member. The second adaptor portion has a second brace member and a plurality of staggered second ribs extending from the second brace member for adjustably mating with the plurality of first ribs for fitting about various diameters of shafts. The ribs preferably have an undercut for allowing a boot or other object to catchably attach and retain the adjustable adaptor. The adjustable adaptor may be utilized with boots, as a bushing or as a seal.