In Wal-Mart, I noticed they are selling replacement bulbs that are kryton and xenon. I always understood the xenons to be better in general which is why I assume xenon flashlights cost more. But these replacement bulbs cost $1.56 for either the krypton OR xenon for a package of 2. They are made by Ray-O-Vac. Are these xenons worth getting as an upgrade to a krypton 2D flashlight?