Abstract: An inertial dumbbell exercise device including a first and second weight assembly disposed endwise upon a handle, each of said weight assemblies including a rod disposed perpendicularly and slidably upon the handle, an interchangeable pair of weights disposed endwise upon said rod, and an interchangeable rubber sleeve disposed between each of said pair of weights and said handle, wherein movement of the handle in a first direction accelerates one of said pair of weights from a first position to a second position against the elastic force of the respective rubber sleeve, movement of the handle in a second and opposite direction accelerates the other of said pair of weights from a first position to a second position against the elastic force of the respective rubber sleeve, and the compressive resistance of the rubber sleeve is adjustable, as desired.