What size of fuse to protect the PID?

I have the Auber SYL-2352 and would like to protect it with a fuse. What size of fuse would be best to protect it?

I read CodeRage's https://www.homebrewtalk.com/f51/electrical-primer-brewers-145019/ and know I want a fast acting fuse. According to the SYL-2352 Manual, the power draw of the PID is <=5W. At 120v, that would mean the amperage would be 0.042A or 42mA. Using CodeRage's 125%-150% rule, I should be looking for a fuse between 52.5mA and 63mA. Is my math correct? Do they even make fuses that small?

Thanks in advance.

Yes they do. You should be able to find them at radio shack.

The last time I bought some I got thees .5A Fast Blow Fuse