Abstract: A single wheelchair selectively mounts at times each of a plurality of different wheelchair seats, one at a time, so as to customize seating upon and within the wheelchair as then best suits the preference of the user-occupant of the wheelchair. Seats support both formal and sport uses of the wheelchair. A detachable sport seat has in particular a deep contour seat base hinged to a deep contour seat back, providing thus substantial lateral support to a seated occupant of the wheelchair.

Abstract: A para-alpine ski, typically a dual-runner sit-ski, has a seat and undercarriage that a user/skier can—under no force(s) save his/her own—cause to raise to a height sufficient so as to permit boarding—totally unassisted if needs be—of the user-skier and his/her entire para-alpine ski onto a moving carry chair of a standard ski-slope chair lift. Upon disembarking the ski slope chair lift the user-skier can lower his/her seat for skiing, again without assistance. When the same sit-ski is used to ferry a total invalid then a trained instructor or guide who normally stands at, and steers from, the back of the sit-ski can stand alongside the sit-ski and its occupant at the point of loading the chair lift, and can trigger the sit-ski seat and its occupant to rise, again permitting that the chair of a standard ski-slope chair lift may be adroitly mounted.