Just curious what the equivalant to the H3 bulb is?

I don't think there is one, its just called H3. I could be wrong

h3=h3

An H4 bulb is also referred to as a 9003 or an HB2.
A 9004 bulb is also referred to as an HB1.
A 9005 bulb is also referred to as an HB3.
A 9006 bulb is also referred to as an HB4.
A 9007 bulb is also referred to as an HB5.
H.I.D. bulbs are referred to as 9500, D2R, and D2S.
H1, H2, H3, and H7 bulbs are usually referred to as such.