This is an early vintage hard rubber Berg Larsen dating back to the early 1940's. This mouthpiece was manufactured before Berg started using the M and SMS, so 90 is all that is stamped for the facing. The piece does have the very early machine markings on the table that were present in the forties before they changed their machines. These super early Bergs are very rare, and this one is in great condition for its age. It does have some light wear on the beak, but other than that it is a really good example of a really early Berg Larsen Duckbill tenor mouthpiece.