Introducing the ULTIMA ZT1 SERIES. Step up to the ultimate all-around mowing experience. The Cub Cadet ULTIMA Series ZT1 50 features a 23 HP Kawasaki FR691V series Twin-cylinder OHV Engine, 2 in. x 2 in. tubular steel frame, comfortable high back seat and much more. The Ultima Zero-Turn Riding Mower was built to raise the bar for enhanced strength, durability, redefined comfort and uncompromised performance.