The 3X55 Trener (Trainer) and 3X47 Ultra are a family of ultralight aircraft produced in Poland by the 3Xtrim Aircraft Factory. Both are two-seat, high-wing, strut-braced monoplanes with fixed tricycle undercarriage and available only as completed aircraft. There are also 450 Ultra and 495 Ultra Plus sub-variants of the 3X47 Ultra, with gross weights adjusted for national ultralight regulations. The US light sport aircraft version of the 3X55 is known as the Navigator 600 and has a 1320-pound maximum gross takeoff weight