From LivingPianos.

https://livingpianos.com/piano-mysteries-the-steinway-model-c/

Welcome to LivingPianos.com, I’m Robert Estrin. Today I’m talking about a piano mystery, the Steinway Model C. You may already be familiar with the Steinway Models B and D, but if not, I’m going to give you a quick rundown. Virtually all new Steinways sold in North America are made in New York. There’s the Model S at 5′ 1", the very popular Model M at 5′ 7", then the Model L (now the O) at 5′ 10 1/2". Then it skips all the way to the Model B at 6′ 11", and then to the concert grand, which is just under nine feet. So there’s a big gap there.