A vehicle seat assembly including a rail pair defining a mounting rail and a triggering rail. This stirrer can perform stirring efficiently, can easily crush and dissolve a water soluble capsule not only in hot water but also in cold water, and can crush a plurality of capsules in a short period of time. The gate is placed over the substrate between the source region and the drain region. when the tilt of the object significantly exceeds a predetermined level, the case fixed at the object is tilted together with the object.