For trade is the extremely rare $5 MK black ringed chip made by USPC. The common chip is the inlay-lifting Burt chip (I do have a nagging feeling that the Burt chip might actually be a pre 1911 Whitehead & Hoag inlay USPC chip)

I believe, subject to correction, that this chip is only the second known $5 MK ringed version

Email me if you have something to trade,