A balance training and exercise device comprises a rigid, shallow disc adapted to accommodate a user’s feet or knees. The semiconductor device includes a metal-made header, a semiconductor chip which is fixed to the header and constitutes a MOSFET, and a sealing body made of insulating resin which covers the semiconductor chip, the header and the like. The fin type transistor may also include a buried stressor andor raised or embedded raised SD stressors to cause a strain in the channel to improve carrier mobility. A groove is arranged in the sleeve, which groove is parallel with the outer periphery of the sleeve and is open at one end.