The SureFlap Cat Flap Mounting Adaptor allows the SureFlap Microchip Cat Flap, the DualScan Microchip Cat Flap & the Microchip Cat Flap Connect to be installed inside glass and walls. When mounting in glass, this accessory allows mounting in circular holes with a diameter of 212mm (min) to 260mm (max). The total diameter of the mounting adaptor is 285mm. Please note: This product is for the Cat flap product range only, and does not include the Pet door. Using the mounting adaptor for wall installations enables you to install the DualScan Microchip Cat Flap more easily because you can use it to fix the cat flap to the wall without the need for messy adhesives. The mounting adaptor is not required to install the Microchip Cat Flap or the Microchip Cat Flap Connect in a wall as these products contain wall mounting screw holes within the front frame. The Cat Flap Mounting Adaptor includes two parts, one for the exterior and one for the interior of your home.