Thank you for your feedback. We apologize about the missing sill adapter. Kindly call us at 1-855-337-8822 with the serial number ready and we will be happy to help. The label is located on the insect screen housing side, either at the top or the bottom of the frame where it attaches to the opening. You will see name Andersen and EMCO, as well as our toll-free contact number. - Charmaine