Abstract: A dumbbell apparatus which is adapted with a series of weight plates, the number of which can be safely and reliably adjusted with a single simple motion. The apparatus comprises a cradle for storing and deploying the apparatus, weight plates, and a handle apparatus which has two spline bolts which support the weight plates and are used to simultaneously be adjusted by means of an adjusting pin which moves the spline members together through a motion transmitting gear. The apparatus may be further enhance with permanent weights and gripping options.