weights 12 base dumbbell 20 includes end parts 22 base dumbbell 20 may comprise at least one magnet chip 16 embedded within surface 21 to which an addable weight 12 can be attached at least part of addable weight 12 may be made of un magnetizable material addable weight 12 may comprise at least one magnetizable chip 14 when comprising more then one magnetizable chip 14 magnetizable chips 14 may be located over an imaginary circle centered substantially at the center of pivot 18 in correspondence with a same number of magnet chips 16 within the surface 21 addable weight 12 can be attached to base dumbbell 20 by coupling magnetizable chip 14 to magnet chip 16 rotation of addable weight 12 relatively to surface 21 may detach magnetizable chip 14 from magnet chip 16 using shearing force and may locate magnet chip 16 against the un magnetizable material and thus addable weight 12 may be released and removed easily from base dumbbell 20 the rotation of addable weight 12 may be about pivot 18 located substantially at the center of surface 21 the perimeter of addable weight 12 may be jagged with jags 13 in order to facilitate easy gripping and rotating of addable weight 12 the use of shearing force makes the detaching.