This is the official attachment for use with the SwitchBot Curtain 3. By replacing the main unit's rail mounting hardware, it can be used with I-shaped curtain rails. Please note that this is not the Curtain 3 main unit itself. - Brand: SwitchBot - Model Name: Curtain 3 Replacement Attachment - Color: White - Type: Curtain opener I-shaped rail attachment Thank you for viewing. I have a cat, so please be aware if you have allergies.