The heavy-duty spring in the base swings the arm so that the molten metal is forced into the flask. The broken arm construction assures that the metal will flow in a straight line, producing dense castings. NOTE: For Safety reasons, casting machine springs must be replaced at the factory. Takes flasks up to 3-1/2" (89 mm) in diameter and 5" (127 mm) high. The long 22-3/8" (568 mm) arm provides the extra force needed for heavier casts. Comes with balance weights and cradle for 2-1/2" (64 mm) diameter flasks. The recommended crucible is the 9 oz. (279 g) size, No. 22454. Shipping weight 20 lbs. (9 kg).