I recently got this cool STM on ebay, inclusive a silver cap and lig. The seller stated (in polish only) that it was made of solid silver, which seems to be true, since there is no brass visible anywhere. Based on the appearance, it is an early babbit model (stm, large font 7 on the side of the mpc). Now I was wondering if anyone knows more about this model, because I could not find any information on the net. When were these made? What was the occasion?