Two D cell batteries
Mounting hardware (Does not apply to PN 1818, as additional mounting hardware is not needed when retrofitting a PM5 to a Model E or Dynamic Indoor Rower, and is optional when retrofitting a PM5 to a Model D. This is reflected in the cost of PN 1818).
Retrofitting a PM5 to a Model D:
When retrofitting a PM5 to a Model D you have two options: to purchase just the monitor (PN 1818) or to purchase the monitor with new mounting hardware (PN 1834).
While the PM5 will fit on the existing monitor arm, the new monitor arm (included with PN 1834) allows for improved monitor cord routing for a tidier overall finished look. The retrofit you choose is up to your personal preference.