Item: Vintage Antique Gold Filled Boston Link Watch Chain Necklace Dog Clip T Bar Slide. This is stamped "Signet" on the dog clasp. It looks gold filled to me.
 
Measurements: 13 & 3/4 inches long. There is the little extra bit of chain for a fob, it measures 1 inch with the connectors. The chain is 2 mm wide. The chain with the T Bar is 1 & 1/2 inches long.
 
Condition: Vintage, previously owned. There are only very minor signs of age/use/wear.