definiens: per unit • or means the Retail Units forecasted by DEY based on detailing by DEY sales force only, and no detailing by CRTX sales force Co - Promotion Fees : After the Commercial Launch Date, DEY will pay CRTX the following Co­Promotion Fees : 1 ) For Retail Units up to Annual Retail Baseline Units ( ), no Co - Promotion Fee will be paid 2 ) Tier 1 : For the fIrst 2.6 million Retail Units above ARBU, Co - Promotion Fee is paid according to the following formula : ( Applicable Retail Units ) x ( Net Retail Average Selling Price ) x 40.0 % 3 ) Tier 2 : For the Retail Units above Tier 1 ( units above ARBU plus 2.6 million units ), Co - Promotion Fee is paid according to the following formula : ( Applicable Retail Units ) x ( Net Retail Average Selling Price ) x 2.3 % 4 ) In the event DEY materially increases or decreases the size ofits Sales Force, the Parties will renegotiate a mutually agreeable split of Net Sales for the Tier 2 Co - Promotion Fee based on the adjusted contribution ARBU : ARBU for 2007 through 2009 is provided in Exhibit A. The ARBU will be reassessed annually beginning in January 1, 2009