The Callowesse Kemble 21cm Extension fits onto the Kemble Standard and Narrow Stair Gates, allowing you to use the Kemble for wider openings. We recommend you to only attach 1 extension on each side of the gate. Features: Extension for the Callowesse Kemble Standard and Narrow Safety Gates Ideal for wider openings We recommend you only attach 1 extension on each side of the gate 7cm & 14cm extensions are also available Please Note: This gate should NOT be overextended to fit larger openings – if more than 50% of the fitting pin is exposed when installed, you will need an extension. We recommend you fully read the Callowesse Kemble Gate manual before installation.