When doing replacement or upgrading on 2000 – 2009 Honda S2000, the bulb size guide is necessary for you to take the reference.
Jump to corresponding car model with the catalog bellow.

Low Beam Headlight 2000 – 2009 D2S
High Beam Headlight 2000 – 2009 H1
Back Up Light 2000 – 2009 7440
Brake 2000 – 2003 7443
Daytime Running Light 2000 – 2009 H1
Front Side Marker 2004 – 2009 12396NA
2000 – 2003 194
Front Turn Signal 2000 – 2009 7440
License Plate 2000 – 2009 194
Parking Light 2004 – 2009 12396NA
2000 – 2003 168
Rear Side Marker 2000 – 2003 194
Rear Turn Signal 2004 – 2009 7440
2000 – 2003 PY21W
Tail Light 2000 – 2003 7443
Map Light 2000 – 2009 DE3175
Trunk 2000 – 2009 168