"When they say 12 volts they mean 12 volts,, not 13.5 "
Except when the product is automotive lighting
. In this case an automotive dome light, which means it is designed for a 14.4 volt power source for normal use, with a nominal 12 volts when the car engine
is off. Perfectly safe for boat use.
How good is it...for that price
? In a non-critical use? Probably good enough.
OTOH when someone says "CREE!" for dirt cheap
, I have to think there are plenty of counterfeits on the market, just like anything else. Lots of profit, and who's going to really know?