The 7 cm extension is ideal for homes with wider door openings or staircases it is compatible with the safety 1st simply close extra tall gate which fits opening widths of 73 to 80 cm when used with the 7 cm extensions this gate covers a maximum opening of up to 94 cm wide please note carefully measure the width of the opening before ordering extensionsto be used in conjunction with safety 1st simplyeasyauto close metal gates