A dumbbell has a planar base allowing it to be supported in a stable manner upon the ground, for instance while the user holding a pair of dumbbells performs exercises such as push ups. A compliant sheet on the base provides a high friction slip-resistant face. A pair of flanges disposed on the base and protruding from the base for mounting a handle therebetween and the base has a waisted form. Weights are provided for adjusting the total mass of the dumbbell. Complementary tongue and groove couplers are provided on each weight and on the flanges whereby each weight is releasably fastened to the device.