A device includes a plurality of ringlets connected together to form a ring having a longitudinal axis. Each ringlet includes a first element and a second element. The first and second elements each extend from a first end through a central portion to a second end. The first and second ends are disposed at radially outer positions with respect to the ring than the central portion. The central portion is longitudinally displaced from the first and second ends. The first and second elements are separated and spaced apart from each other at the central portions thereof and are joined together at the first ends thereof and the second ends thereof. The ringlets are connected together such that the first ends of the elements of one ringlet are connected to the second ends of the elements of an adjacent ringlet.
