This is the reference page behind every verdict the checker returns. It works through the five specifications that decide whether an implement fits a compact tractor, in the order a buyer should check them: hitch category and pin diameter, minimum PTO horsepower, PTO shaft speed, implement weight against usable three-point lift capacity, and the extra clearance and geometry limits that apply to sub-compact tractors. Each section explains what the manufacturer figure actually measures, where it is published, and the mistake it most often causes at the dealer, such as reading engine horsepower instead of PTO horsepower, or comparing implement weight against a lift rating measured at the wrong point. Front-mount attachments are covered separately because loader quick-attach type and hydraulic remotes govern fit there. A printable pre-purchase checklist is linked at the end.