Abstract: The invention (49), an adjustable instability apparatus for exercising, balancing, recreation and physical rehabilitation activities, is described comprising an air spring assembly (48), a bleeder valve with seal assembly (46), a bearing assembly (66) and flanged button head cap screws (38). The air spring assembly (48) consists of a molded rubber resilient inflatable bladder (22) that can be selectively inflated or deflated, and is surrounded by a girdle hoop (80) filled with multiple strands of wire (24) which are molded into the resilient rubber bladder (22). A substantially round, flat and rigid top plate (20) equipped with multiple threaded blind nuts (28) is crimped and sealed to the top portion of the bladder (22). A substantially round, rigid bottom plate (26) with the central portion concaved inward having a threaded open nut (88) with multiple threaded blind nuts (28) is crimped and sealed to the bottom portion of the bladder (22).