It seems you can use any bank's card reader meaning you don't have to keep several different readers at hand or bulging out pockets when away from home. I found this by accident when I couldn't find my Barclays reader but had my mum's Nationwide one. I then found I could mix/match. It's not something I've seen in any gumph from any banks before although Barclays indicate that you can use anyone else's Barclays reader. It seems they are all built to the same specifications although a quick Google search indicates Santander's are a little different but that was a couple of years ago so may have changed by now.
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