threaded hole. A cotter pin or a couple of loops of mousing wire through this hole serves the same purpose and secures the shackle in a closed position. Nylon zip ties are also commonly used in applications where the shackle must be secured but easy removal is required. Use A safety wire is used to ensure proper security for a fastener. The wire needed is long enough to reach from a fixed location to a hole in the removable fastener, such as a pin — a clevis fastener, sometimes a linchpin or hitch-pin through a clevis yoke for instance — and the wire pulled back upon itself, parallel to its other end, then twisted, a single end inserted through a fastener, and twisted again, possibly then anchored to a second fastener or other part, then twisted once again, having excess slack pulled relatively taut to be secure. The two ends of the wire-loop thus formed are joined by twisting them together with a tool, using enough twists to be secure, then released from the twisting tool. The removable fastener — possibly a nut, wing nut, turnbuckle, a bolt or a pin similar to a bolt — having a hole through a part of it that will remain accessible when it is fastened in place will be secured with the wire passing through it. When finished, any excess length of wire would be cut off with a pair of wire cutters, such as pliers that may, also, be the twisting tool. If the fastener part to be secured does not come with a hole for the safety wire, one may need to be drilled. Safety wire is not reusable, thus it can be cut apart in order to remove it easily when the fastener is to be opened. Proper techniques When using a most common gauge of safety wire, which is 0.032 inches, guidance for installation can be found in several publicly available sources. identifies only 6 to 8 twists per inch. 43.13-1B has no other reference to twists per inch either by hand twisting with special tools. identifies different twists per inch as 0.020–0.025 inches at 8–14 twists per inch, 0.032–0.041 inches at 6–11 twists per inch, and 0.051–0.060 inches at 4–8 twists per inch. The safety wire should be threaded through the object fastener such that it creates tension in the opposite direction of the fastener's removal. For example,