A selectable weight dumbbell system may include a base and a dumbbell. The base may include one or more weight receiving spaces defined by the base's walls and floor. The dumbbell may include a handle and one or more selectively removable weights. The weights may be removably positionable in the weight receiving spaces. A weight and the base may form an orientation feature or key between the weight and the base that compels the weight to be positioned in said one of the weight receiving spaces in an orientation for selective engagement with the handle. The orientation feature or key may include an orientation element, such as a protrusion or the like, and an orientation receiving element, such as a groove or the like. The orientation element may extend from the weight or the base. The orientation receiving element may be defined in the weight or the base.