1.25" is without backpaper as issued. This was one of the companies of inventor and manufacturer George Westinghouse, organized in 1881, devoted mostly to the manufacture of gas and steam engines, turbines and mechanical stokers. The plant covered 20 acres and employed around 3500 men by 1905. That is likely the date of this button as the spelling of the city name is without the letter "H" on the end as used during the years 1891-1911. NM, displaying Mint and the only example we've seen.