Ive seen a good pic somewhere of the bulb and it did have a support in the middle. Will try to find it.
https://www.hdforums.com/forum/dyna-...star-h4st.html
Motorcycle specific h4 bulb.
http://www.ebay.com/itm/H4ST-Sylvani...#ht_8477wt_952

 

I just added an album to this forum of some close up pictures of the internals of H3 bulbs I had in my bulb drawer. I worked for Valeo (OSRAM now Sylvania) for a year in their lighting division and had access to a lot of different bulbs they made. The Silverstars or Ultras were not around then. I used 100 watt bulbs in my high beams on most of my cars and used Valeo's high performance reflectors. After a year or so the high watt bulbs would boil/vaporize the reflectors aluminum coating. I ran 100W/80w H4's on my Shovelhead and had the same problem it just took a little longer. I labeled the pictures with Sylvania Ultra, Stock HD 1 & 2, and standard H3, and add Ultra. I did not have a Standard Silverstar here but looked at them in the store and they looked just like the Standard H3 in the picture. You can plainly see the glass bridge tying the metal filament support rods together in the Ultra's and the stock HD bulbs and not on the Standard H3. This is why I decided to try the Ultra's after reading so many complaints about the lifespan of the Silverstars on this forum. I would like to see their Motorcycle bulbs structure but the light improvement claims are not as high as the Ultra see photo add Ultra. The add has 9006 bulbs but is the same print as the H3.