Retro-fit sodium for mercury replacement

This example is of the Philips 350W SON-H retro-fit for 400W MB-type mercury lamps. Requiring no modification to the mercury control gear. The lamp offers an increase in luminosity and a reduction in Wattage. I think this example is from 1994 and the internal starting aid is as depicted in my Philips 1984 lighting catalogue (insert). A printed PCA tube printed starter track was introduce later a long with a solid-state getter.