From the 1949 Selmer Paris Catalog:
No mere advertising description could add to the towering reputation of the Selmer clarinet. It has been generally accepted as the standard by which all others are judged. If you are among the many artists who play a pre-war Selmer, you most likely think it could not be improved. Yet our tests and many made by leading professionals show that these latest clarinet to play for the ultimate in tone quality, positive tonal placement, improved tuning, and sensitivity of response. Lifetime Power-Hammered mechanism, of course. All Models are Boehm system, of finest Grenadilla wood.