| 摘要 |
A buttocks seat is supported by a post tiltably affixed at a lower end to an upper face of a base. The post is also axially rotatable relative to the base, and threadably engaged with an underside of the seat for supporting the seat on the post, the seat squarely facing upright when the post is vertical. A hand wheel is affixed to the post for rotating the post relative to the seat and the base for selectively raising or lowering the seat relative to the base. A resilient bias urges the post to be vertical unless a seated user flexes his or her lumbar with sufficient force to overcome the bias. Preferably the post is tiltable over a conical range and the bias comprises a resiliently compressible, cylindrical ring coaxial with the post, and extending between and abutting the base and the underside of the seat.
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