GP Batteries E Block 9 V Lithium Battery: Amazon.de: Electronics & Photo
VARTA Longlife Power 9V Block 6LR61 Alkaline E-Block Battery (1-pack) - Made in Germany - ideal for fire alarms, smoke detectors, tuners: Amazon .co.uk
ANSMANN 9V Industrial Alkaline Batteries [Pack of 10] Long Lasting High Capacity Square 9V E-Block Battery For Household Appliances and Industrial or Laboratory Equipment: Amazon.co.uk: Electronics & Photo