Cast brass or bronze. Reads: BANGOR EXTENSION LADDER JOSEPH S. SMITH BANGOR, MAINE PATENTED MARCH 23 '75 MARCH 26 1878. About 7 7/8" x 3 3/8". Probably came off an old extension ladder. Smith's patent had to do with long attached arms that folded out like wings on the side of tall extension ladders to give them support when used on tall buildings - before that firemen used loose poles to prop up ladders. As pictured.
 

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