2 x Unit GP23A 12V Alarm Remote Alkaline Battery High Voltage 21/23 A23 MN21 4891199042140 | eBay
Duracell Specialty Alkaline MN21 Battery 12V, pack of 2 (A23 / 23A / V23GA / LRV08 / 8LR932) designed for use in remote controls, wireless doorbells and security systems : Amazon.co.uk: Electronics & Photo