Discounted pricing applies to full 600' rolls only. Regular pricing applies to any length of curtain purchased that is short of a full roll.
Example:
Full Price = $1.05/ft
Full Roll Promo Price = $0.90/ft
A purchase of 700' of this curtain would be calculated at (600' x $0.90 = $540.00) plus (100' x $1.05 = $94.50) for a total purchase price of $634.50 before taxes and freight charges.