Speaker binding posts with plastic covers

They aren't for personnel safety and not required by any code, they are to protect your amp from accidental shorting which is the most common cause of amp failure.  (Everyone says "it just failed!!!").

Usually you can unscrew them with your fingers and put a spade in. 

Jerry

If they just unscrew, then they are very very tight. I'll get some heavy gloves and try again. 

If all else fails, send an email to the manufacturer?  

just unscrew... they may be screwed on tight from the factory,,, work them loose with a firm but gentle hand

They unscrew, but not the whole thing. The spade actually goes between the bracket looking portion. If you are trying to unscrew the entire thing you will break it. Just unscrew from the top of the connector. Should unscrew pretty easily,