US Patent 7731641 Adjustable dumbbell

An adjustable dumbbell includes a handle having a narrowed neck segment formed on each end portion and having a base plate attached to each end portion, two or more weight members each having a slot for receiving the narrowed neck segment of the handle, and each having an enlarged opening communicating with the slot for receiving the handle and for retaining the weight members to the handle when the weight members are offset from the narrowed neck segment of the handle, and a lock nut is engaged with the handle for quickly retaining the weight members to the handle after the weight members have been disengaged from the narrowed neck segment of the handle.