Replacement Springs for Upright Hammer Butts. Available in two different sizes: Either with a 1-3/4" tail or 2" tail. We also have spinet hammer butt springs available with a 1-1/8" tail. This is measured in a straight line from the coil to the point where the wire rests in the hammer butt groove. Please choose size. Available in sets of 12 or 100 springs.