Abstract: A tool for engagement with the periphery of a cylindrical device includes a rigid, outer band supporting a flexible, split, inner band having deflectable, arcuate, distal portions joined by an actuating arm having a free end disposed substantially along an axis extending through the center of the bands and the cylindrical device. A pair of link assemblies having one end fixedly mounted upon the outer band having their opposite ends joined to the inner band distal portions and are slidably engaged by the actuating arm such that arcuate displacement of the arm free end shifts the link assemblies to contract the inner band and produce a rotary displacement of the entire tool.