The World's Finest Trimmer's big brother is designed for the really big cartridges, up to 50 BMG. Same top-quality, precision components, but beefed up for harder work. It requires a drill with a A 1/2" chuck and it's set up a little differently from the WFT. One heavy-duty trimmer body accepts any one of the interchangeable trim chambers, so you buy the body once, then the trim chamber for the cartridge(s) you're working with. Mfg: Little Crow Gunworks.