Keyed and indexed embossed tube and taper lock system

A wheelchair comprising:

• a frame comprising at least one tube and an indexed structure comprising a concave keyway formed in the at least one tube and concave dimples formed within the keyway, the keyway extending in an axial direction along a side of the tube, and the dimples being incrementally spaced apart in the axial direction within the keyway;
• and
• at least one coupling configured to selectively connect to the tube to allow adjustment in the coupling, the at least one coupling being configured to couple a wheelchair component in relation to the frame,
• wherein the at least one coupling comprises a clamp comprising an at least partially cylindrical passage defining an inner wall that is configured to at least partially encapsulate the tube, and a keyed structure to cooperate with the indexed structure of the tube, the keyed structure comprising a convex key which protrudes radially from the inner wall and one or more spring-biased plungers disposed within the key that respectively mate with the keyway and dimples in the at least one tube, whereby the coupling is positionable at specific points in relation to the tube, wherein the one or more spring-biased plungers are spring loaded to extend from the key to selectively engage the dimples, and
• wherein the clamp is tightened against the tube by manipulating at least one fastener so as to be prohibited from moving along the tube and such that the one or more spring-biased plungers securely engage the dimples, and wherein when loosened, the clamp is movable along the tube while the one or more spring-biased plungers selectively and discretely engage the dimples to provide an audible or tactile sensation indicative of an incremental movement of the coupling.