The Draper D20 Roller Shade Clutch, also known as the gear mechanism, is for roller shades with Flexshade or RollEase tubes that measure 1-1/2 inches outside diameter and with a face width of 2-15/16 x 3-1/16 inches. It’s available in white or black. Lastly, for operation use the #10 nickel plated steel, stainless steel chain, or plastic chain. Can fit 2 inch tubes with an adapter.