My searching leads me to believe this is an advertising chip intended for BTS Research Co. in San Diego. This company provides medical studies to drug companies. Their logo is shown below the chip pictures.

Two different colors of Reliable Engraving PMSC chips: black and green. Reverses show flat brass centers. Oversize 1 5/8" diameter chips.

Offered at $25 each for your choice of color, or $45 for both. Price includes delivery in USA.