Flight models of the filter-wheel assembly (FWA, left) and the grism-wheel assembly (GWA, right) before integration into NISP. Both wheels contain the same cryo-motor and bearing system, but have their individual mechanical design. Each contains an open position to allow light from the other mode to pass. The FWA has one closed position, blocking the telescope beam into NISP for dark and flatfield exposures, and one filter each for the Y_E , J_E , and H_E passbands. The GWA has three grisms for the RG_E passband, at three orientations, and one for the BGE passband.