The IS® 4500Z series provides you with pure mowing performance. Available with your choice of diesel or gasoline engine options, the IS® 4500Z features our patented suspension system. The 72" option is paired with a powerful 35-hp Vanguard BIG BLOCK liquid cooled engine. Folding Roll Over Protection System (ROPS) is a standard feature with a retractable seat belt. There is not another product in its class that can match the power and performance of the IS® 4500Z.