used to belay, temporarily tie off, the rope lines of a hemp system. Each belaying pin serves as an anchor to which the loose end of a rope may be quickly secured. A standardized method is used to tie off the rope so that it is subjected to friction from itself as well as from the pin rail, thus ensuring a secure connection that is unlikely to fail. Belaying pins are typically made of hickory wood or steel. Knots, such as the clove hitch and half hitch, are used for rope line terminations. For example, hitches are used to terminate hemp lift lines at battens and operating lines at counterweight arbors. Rope locks are cam-actuated devices through which a counterweight system operating line passes. The adjustable cam, or dog, inside the rope lock constricts and releases the operating line as the flyman lowers and raises a hand lever. Rope locks are mounted in series to the locking rail. A single rope lock can typically secure a static unbalanced load to . Rope locks are not intended to slow a running line. Swage (compression) fittings or cable clips are used to terminate counterweight system lift lines, after the cable has been looped around a thimble. Cable clips terminations maintain less load capacity than swage fittings, typically require three clips, and are greatly reduced in load capacity if the installer happened to "saddle a dead horse". Both swage and cable clip terminations permanently crimp (deform) the wire rope. Trim chains and shackles, or turnbuckles and pipe clamps, typically connect the lift lines of a line set to the batten they support. Those connections facilitate minor adjustments to, trim, the effective length of a lift line. By trimming the lift lines, loads are more evenly distributed to them. Turnbuckles are moused (secured against free rotation) to prevent the jaws from slowly unscrewing over time due to vibrations incurred during normal use. Counterweight lift lines typically connect to the tops of arbors with shackles. Blocks A block is a pulley used to support and direct lift and operating lines. A block consists of a grooved wheel, known as a sheave (pronounced "shiv"), steel side plates, spacers, shaft, flange bearings, mounting angles and clips, etc. Blocks are sized based on anticipated live loads, operating speeds, line type and other factors. Sheaves were traditionally fabricated of cast iron, but steel and nylon sheaves are now common.