A measuring device is provided that may be selectively configured between an extended condition and a collapsed condition. The device includes a first member, second member, flexible housing, and securing means. Each member has a proximal end, distal end, and convex surface. The convex surfaces are flexible such that the members may bend about a bending axis of the device and resilient such that the convex surfaces are biased toward their stable convex shape and the device is biased toward the extended condition. The first and the second members are disposed within the flexible housing to form a covered pair having a proximal end and a distal end. The apex of the convex surface of the first member is opposite the apex of the convex surface of the second member when the members are disposed within the flexible housing. The securing means secures the measuring device in the collapsed condition.