Sheaffer offered the Model 15 dual pen desk set for perhaps 15 years, changing the style of socket, but keeping the basic black onyx base constant. The earliest were made in 1925, but this one probably dates from 1930, based on the socket styling. It is fitted with the earliest style of swivel socket, one rimmed in red, and matching white dot Lifetime pens, one trimmed in red. One of the dual pens would have been filled with blue or black ink, and the other with red. The trim rings kept things properly organized.
The Model 15 was the big brother to the single pen Model 10, which also enjoyed a very long life in the Sheaffer lineup.
My Model 15 is in excellent condition, completely free of “flea bites” around the edges of the base and with intact sockets. The pens also are in pristine condition, but require some nib work and new ink sacs to make them functional again.