eScrap Component Identification

I thought #2 were voltage regulators(the ones i have have voltage marked on em some in dc, some in amps). Does 4 say relay on it or does it give a uf number(ie: .2uf). If it says relay on it it's a relay, if it says uf(unifarads) it's a block capacitor.

To clear up a couple of points, #2 is called a bridge rectifier (can take 120ac and change it to 12dc volts at whatever amps it is marked). Second point is if it's marked uf then that's the symbol for microfarad (I believe that's a millionth of a farad).