The ones that came in my bike (two bulbs, interstate) were Kuryakyn Rainbow Strobe (it does not flash). VA is so traffic Nazi on DOT and inspections, I pulled mine out. It is not actually a bulb, it is a cage that goes around a std H4.
Looking at the Kuryakyn site, they may no longer be available. But if your H4 bulb is gone, you can probably replace it and reuse the strobe cage.
The Rainbow Strobe is a small cage assembly that slips over an H-4 style halogen bulb, creating a colorful pattern within the headlight. Although the beam is, for the most part, unaffected, some blue, green, and red coloring occurs. Installs with ease. Check regulations for suitability in your area. For use with H-4 halogen bulbs with three prong base. https://www.phatperformanceparts.com/ProductDetails.asp?ProductCode=2141&HistoryRemove=ALLPS, my bike used std auto parts H4s with tabs cut off the base, and still fit the Kury strobe cage. I had the Custom Dynamics support rings (for cut tab H4s), but could never get them lined up with new bulbs in the IS fairing, and now leave them out.