An apparatus for applying an optional number of weight disks on a
dumbbell includes a base unit, a first and second set of separate weight disks and a
handle. The base unit has a first and second group of retainers which support the first and second set of weight disks. On the
handle, a selectable number of weight disks are disposed from the first and second set of weight disks. The weight disks have openings which are closed towards the peripheries of the weight disks. The
handle has pin devices which are axially projectable in opposing directions for
insertion in the openings of the weight disks. The projection of the pin devices out of the handle is selectable for
adaptation of the length of the pin device to the number of weight disks that are to be secured on the handle. The pin devices are further lockable with locks, in selected projectional positions in relation to the handle, and have, on their free ends, locks for fixedly retaining the selected number of weight disks.