The most popular bulb used is the H7.  The H7 will fit both the dipped and main beam on many bikes.

The BMW R1200GS uses the H7 for both dipped & main Beam.  The BMW Aux/Fog lights use the H11.

Most of the BMW F800, R800, S800 etc also use the H7 for both dipped and main beam.

Most BMW R1100GS & R1150GS use the H1 for both dipped & main beam.

If you are unsure, please check with the manufacturer which bulb/s your bike requires.

H3 & H4 kits available soon