Exmark VERTEX X Series Operator's Manual page 38

Maintenance
WARNING
Incorrect installation of the blade or
components used to retain the blade can
be dangerous. Failure to use all original
components and assembled as shown could
allow a blade or blade component to be
thrown out from under the deck resulting in
serious personal injury or death.
Always install the original Exmark blades,
blade bushings, and blade bolts as shown.
38