Plomb Tools ( Proto’s predecessor ) was founded in Los Angeles, California in 1907 by Alphoso Plomb, Jacob Weninger, and Charles Williams.  Its earliest tools included items such as hand-forged chisels and punches, intended primarily for the plumbing and building trades.  It had very good reputation in making professional tools.  So good that the name, PROTO, was derived by combining the first few letters of the two words that described its products: PRO-fessional and TO-ol.

This item has Proto trademark logo with the registration number 0501030 applied by Plomb Tool issued on July 13th 1948.