Tripoint US 3 colour pencil

Does anybody know whether these Tripoint 3 colour pencils were
manufactured in quantities, and over what period?

http://www.box.net/shared/static/asizegqnlj.jpg

Length is 13.8 cm (5 1/2 inches).

The pencils takes the Norma sized leads of 1.18 mm..

The selected colour is advanced by sliders, that twist round into a J
lock. Then the lead can be advanced by twisting the whole base. The
end cap covers an eraser.

Stamped into the black plastic are the words:

NICHOLS PRODUCTS Co.
MOORESTOWN N.J.
PAT. U.S. 1730679
SAN.318395

The US patent was applied for in 1927, which is rather earlier than I
had anticipated from the appearance of the pencil.