When Good Ergometers Do Bizarre Things - MaxRigging
Concept 2 PM4 monitor rechargeable battery pack (model D & E rowing machines) - GymStock
LiveRowing Concept 2 Connector for Apple Smartphones - Rowing Machine Accessories for Your PM3, PM4, PM5 Erg Machine - Plus Free LiveRowing App - (Cradle NOT Included, for Apple Devices ONLY): Buy
PM4 Concept 2 Parts and accessories - Concept2
PM4 Performance Monitor Retrofit Kit for Model C Rower, Concept 2 - Sportsmith