They are a standard H4 bulb. The only difference I can see is my CK30 manual advises to use a 25/30 watt bulb, where normal vehicle bulbs are 55/60 watt bulbs for low/high beam. I don't know if the wires aren't heavy enough or they are worried about heat build up. Maybe an auto parts store would have the lower wattage due to them being a standard bulb design.