Looks like those already matured, so 4% is what they will actually return, with no future doubling of principal. They will stop paying interest on the dates you noted.
4% nominal is not a great return based on past history. However, your bonds have 1) similar yield to corporate bonds of the same maturity, 2) no default risk, 3) no interest rate risk, 4) no market risk, 5) immune to state and local taxes, 6) deferred federal taxes until redeemed. That makes them a better deal than you will find anywhere in the bond market. I would use these for your bond allocation until just before they end interest payments, and redeem them over a few years to minimize taxes. If you do not want a bond allocation or you want a much smaller one, then sell them to match your allocation. I'm not so much into the market timey thing, you might get lucky but the odds are against you.