My uncle in Farmington called me this week and said he got a letter in the mail from Comcast saying that by August everyone will need a digital converter box to receive all channels above channel 25. The letter said Comcast will be providing 1 digital cable box and 2 digital adapters free of charge. What exactly is a "digital adapter"? He has 3 TV's that he needs to connect, so he doesn't know if these items will be sufficient.