shoulda got these ones...
Why's it surprise you? It's a standard ISO size that most manufacturers used for pop up headlights. RX7, MR2, Z31, 180SX, MX5, S12, Prelude(or is it integra?) all use the same.
don't put HID's into non projectors you gimp. You'll blind every kent on the road with your badly focussed beams.