Boye #7 vibrating shuttle bobbin.  Single bobbin for National and Domestic models.  Unique bobbin with holes in ends for bobbin winder pin.  Bobbin measures 1 1/2" long with 1/8" shaft and 3/8" diameter ends (with holes). Near new bobbins ships free (price includes shipping).  Return for refund if fail on your Goodrich SMC Newark model or National Conquest, Domestic or Reliable.  May work on other models as well.