This hatchet is often mistaken for a wood shake or shingle roofing hatchet. It is for installing 3- tab roofing. The missing gauge pin was used to set the exposure, usually 5". The bottom was sharpened to cut the shingles instead of a gyp knife (Old carpenters name for a utility knife. Utility knives were first invented to cut gypsum board. Gyp board is a 20th century invention, the earlist I found was installed in 1929 and the joints were covered with 1/4" x 2" wood strips instead of tape and mud) These hatchets came after 3 tab roofing and were never around before that. Historically never used for wood shingle roofing or lathe and plaster work. They are used today for wood shingle roofing because roofers do 3-tab and wood shingles, so the line got blurred .