Cart Shopping Cart My Store Account Orders Downloads Shopping Cart Remove item Thumbnail image Product Price Quantity Subtotal × 1. Weight Economy $20.00 1. Weight Economy quantity $20.00 × 30. The Effect of Center of Gravity on Performance $20.00 30. The Effect of Center of Gravity on Performance quantity $20.00 Coupon: Apply coupon Update cart Available coupons (Click to apply). Cart totals Subtotal $40.00 Tax $0.00 Total $40.00 Proceed to checkout