The JWST flight instrument MIRI (Mid Infrared Instrument) was delivered from the European Space Agency to NASA/GSFC on May 29th, 2012. Following this major project milestone, the second JWST flight instrument NIRISS/FGS (Near Infrared Imager and Slitless Spectrograph / Fine Guidance Sensor) has also been delivered. NIRISS/FGS was assembled by the Canadian Space Agency.
More information on the instrument's characteristics and science potential can be found here (NIRISS, FGS).