The color of the bearing determines the sash weight range of the balance. The length of the balance is determined by measuring the length of the tube ONLY, and do not include the bearing or rod in the measurement. The rod is a standard rod which extends beyond the tube by 5/8 in. The tube diameter is 3/8 in. Make sure your balance matches the specs of this balance before ordering. Specific ends and accessories should also be ordered and replaced with new balances.