The 18" Aluminium Arm Parallel Rule features aluminium arms and handles. The parallel rule is manufactured to a 1/4" thickness and 18" length. The high-quality construction of the parallel rule is backed with a lifetime warranty.
An essential item in any proper navigation kit, the parallel rule is used to plot direction on your nautical chart. The parallel rule is, essentially, comprised of two straight-edges hinged so that they maintain the same angle. By alternating the moving edge, and securely holding down the non-moving edge, you can move the parallel rule about the chart while still maintaining the same angle.