The model is called the Dollar, because, of course, the pens cost a dollar, so the pencil probably cost the same or less. It was a model made from 1934 until 1942. Dollar models can be identified by the clips with the oval cut-outs. From 1934 to 1937 the clip had a taper at the top, and from 1938 to 1942 the tops of the clips were the widest part, like this little pencil's.
The small size pen and pencil were known as the demi model H. On this H pencil, you can see the imprint has a fancy script H. The imprint says, " R Esterbrook H, PAT. MADE IN USA."
Dollar pens and their matching pencils had two other models: the slimmer A, and the regular size, B.
But you can hardly beat the baby blue model.
Here is my first post about Esterbrook: New To Me
To learn more about Esterbrook pens: Esterbrook.net