The one I suggested besides being cheaper is less likely to accidentally be switched to the wrong voltage unlike the first one you suggested (which also has more plug options for other options including the USB-C connector now becoming standard for cellphone and many devices) . But if the plug and voltage (which seems rather vague) were correct the second one you suggest would be simple and cheap. However, some items over-voltage by the amount possible with this may not be harmed immediately but may run hotter shortening their life. I definitely strongly agree with your suggestion of checking the voltage is good advice--particularly the second one as that voltage, if having no regulator, may go as high as maybe 13.8 volts (about a 50% over-voltage). Note the manual below does say he should use an adapter to 9V if using a car at 12V so giving it the higher voltage sound like a bad idea.
GRE PSR-500 Manual Online: using ac power, Using Vehicle Battery Power. You Can Power The Scanner Using A Supplied Ac Adaptor. Warning: You Must Use The Supplied Ac Adapter. • Always Connect The Ac Adaptor To The Scanner Before You Connect It To Ac Power. When You Finish, Disconnect...
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