Shaw - Barton started making pencils in 1940 when they purchased a calendar company (making other specialty advertising items, as well) in their hometown of Coshocton, in east central Ohio. This is a slim 1940s middle twist pencil, using the recently introduced slim lead (0.9 mm). It is 5 inches long.
The top "jewel" is crackled transparent yellow plastic, maybe Lucite, an acrylic-based plastic.
Other family A-E pencils can be seen here: More Sheaffers in the Waterman Family Desk