The seat body has a projection member (32) projecting toward the foundation and also has an operation member (31) capable of adjusting the amount of projection of the projection member.
A tip of the projecting section protrudes from the tubular enclosing section.
Other species visualized are spring loaded projection, frictional slide projection, a swing projecting arm, and detachable retention pins.
The resin member (4) comprises a projecting part (4b) projecting from the opening (5g).
Each of the holes (4) has formed thereinside a projection (5) having a flat or projecting upper end surface.
The protruding section (3) is provided with first protruding bodies (31) and a second protruding body (32).
The protruding area comprises a first protruding area (203) and a second protruding area (205).
The amount of protrusion of the protruding part (6) at the corner-cutting-edge side is less than the amount of protrusion of the protruding part distant from the corner cutting edges.
The second protruding body (32) protrudes slightly less than the predetermined dimension of the first protruding bodies (31).
The swollen section (42) is provided with a most swollen section (42M) which is a portion swelling inward the most in the radial direction.
Non-projection parts (N) with no any projection are formed near a belt line, and the projection parts (14) are formed at other positions.
The body to be detected is provided with a protruding section and a shaft section connected to the protruding section.
The projected portion (2) is molded so as to protrude toward the supporting member (4).
The first protruding bodies (31) protrude only a predetermined dimension, and extend in the vertical direction.
The other of the projections (14) is harder than the projection (11) made from rubber elastic material.
The protrusion member (130) defines at least one protrusion (136, 138) extending outwardly therefrom.
The partition wall (40) protrudes towards one side forming a protruding column (42).