I have noted that almost all the american made incandescent lamps that described as krypton filled lamps, have just a regular pear shape instead of the mushroom shape that accepted in Europe.
They also have usually too much life as krypton filling can be offer (>8,000 hours instead of 1 year or ~2,000 hours of the european krypton filled mushroom lamps).
The reason for the mushroom shape of the krypton filled incandescent lamps in Europe, beside decoration as they promoted initially, is mainly to reduce the required volume of this expensive gas. This gas offers 10% more light and 50% more life then argon (
http://www.lamptech.co.uk/Documents/IN%20Gases.htm).
So, are the american pear shaped lamps that described as krypton are really krypton filled lamps, or that they are a deceit, and these lamps actually argon or nitrogen filled and are actually severally underdriven?
Picture of a GE hungary 230V 60W typical european krypton filled incandescent lamp can be seen here:
http://www.lighting-gallery.net/gallery/displayimage.php?pos=-41796 .