Spiral rod length when fully extended.

Can you tell me the length of a red S500-26 from the top of the balance to the bottom cross member with the spiral fully extended? I need to know this length to see if it is long enough for my bottom sash to close. On some of my older windows the spiral balances are the same length for the top and bottom sash even though the top sash is one inch shorter than the bottom sash. Thank you in advance for your assistance.