Delta Blinds Supply Cord Lock Mechanism for Horizontal Window Blinds This mechanism will allow your blind to lock into place while lifting or raising it. Instead of locking your blind into place by pulling the cord to the left or the right, this mechanism allows you to pull cord straight up or down to lock into place. Fits securely in a 2 inch tall and 2.25 inch wide headrail. Instructions on how to replace your cord lock is near the bottom of this page in the "Product Description" section.