A171 820 25 26 and the replacement A 219 820 32 26 are both getting old. New ones are unobtainable and used examples expensive, considering that when you take them apart to replace the batteries you're likely to find them fried. A2048705726 is more modern and there's a plentiful (cheap) supply of used ones. Casing isn't quite the same and the connector different (although still 3 terminals). Does anyone know if it has the same PCB?