Abstract: A termination device for a flexible tensile strength member has an internal surface which defines a passage through the device. The profile of the internal surface is a constant-radius arc extending from one end of the device to the other end. The radius of the arc emanates from a point of origin located along a line that is both collinear with an end of the device and perpendicular to its longitudinal axis. The design can be optimized either to provide a minimum device outer diameter while generating a high efficiency (greater than 90 percent), or to generate maximum possible efficiency within a device that is minimized in diameter (and wall thickness) while preventing device failure.