This button is unique in that it was used only at the "Preferred Class Penitentiary (Ontario)" in Kingston, as indicated by the "PCP" monogram. This facility opened in 1930 and was intended to house the "more reformable" or "white-collar" criminal. Staff uniforms, at least for the senior ranks, were dark blue with a red stripe on the outer pant leg, as opposed to the paramilitary khaki green uniforms of the other federal penitentiaries and lower ranks. This unique designation only lasted for 3 years. In March of 1932 the facility was renamed "Collin's Bay Penitentiary" and was reclassified as a general population facility.
The button appears in brass as well as white metal and in two sizes. Brass examples appear to be generally back-marked "Made in England".