Replacement mini halogen 12v DIMMABLE In a boat, caravan or car there is normally 12V present, the 12V LED lighting works perfectly there and it is good for the battery life. 230V is present in houses and shops and then a transformer is needed. You will find this at accessories. Our G4 LED are perfectly dimmable. They are resistant to 10v - 18v, which causes defects at other peaks in these brands. Just take out your halogen lamp, the LED G4 lamp in it. It's that simple.