Seat Stop Upgrade to be used with Canoe Paddling Adapter. PVC tubing slides through the Concept2 metal Seat Roller Frame and then clamps to bottom of Concept2 Rower Monorail, allowing for quick adjustments in seat position. Especially helpful in club or gym settings to accommodate multiple paddlers of varying leg lengths. Designed to fit on the Models D and E Indoor Rower and the RowErg (see photo). Only one seat stop is required per Paddling Adapter.