Abstract: A telescoping tube assembly of adjustable lengths comprising two or more elongated tubular members with a locking mechanism designed to retain the tubular members and desired relative relationship one to another. The locking mechanism includes a truncated conical expander head with a cylindrical body segment and a conical tip segment, with the expander head functioning cooperatively with a radially expanded frictional break member. A square head (or head of other non-circular configuration), is used to cause relative rotation between the conical expander head and the radially expanding brake member. Annular hinges are provided between the cap portion and the radially expanding friction shoes of the break member, with the integral annular hinges flexing in opposite directions to provide broader area of contact between the internal peripheral of the tubular member and the outer surfaces of the frictional break member.