[SpudRider]

I have an important caveat for those installing the H4 headlight bulb in a Zongshen RX3 motorcycle.

The base of the H4 bulb is almost identical to the stock HS1 bulb; however, there is one important difference. Both bulbs have two small tabs projecting from the base, but the tabs on the base of the HS1 bulb are spaced wider apart. Both bulbs make a tight fit when the bulb retainer is twisted into the locked position. Therefore, It is important to either flatten these tabs, or twist them off the base of the H4 bulb. Otherwise, when you twist the bulb retainer over the H4 bulb, you might crack the reflector.