The MacGregor Factory now uses a one size fits all mast. They discontinued making the 'M' mast due to the extrusion process, something I discovered when trying to obtain a replacement mast. I was informed that they now use an extusion process that is easier and produces a mast that is stronger but less stout and will fit all previous models. You need only to cut it to size as they are manufactured in 30' lengths to fit the tallest M model and all other shorter ones. Check with your nearest dealer.