This pocket watch fob is from Harry Griffith jewelers, a Milton business existing prior to the 1880 fire. The piece would have been given to customers to market the business and would be used to open the back of the watch for winding. The top section of the fob is shaped like the Pennsylvania keystone.
Harry Griffith Jewelers
Harry Griffith Jewelers, “Watch Fob,” Pennsylvania History Harvest, accessed December 18, 2018, http://pahistoryharvest.com/items/show/283.