AR-18 STARRETT RULE 18" The AR-18 18" Aluminum Rule is a parallel rule made of anodized aluminum. FEATURES Designed to meet the general-utility measuring needs of schools and shops, woodworkers, tinsmiths, metal workers, and bench applications They lie flat, resist bending and feature large , easy-to-read graduations and numbers that are heavier than conventional machine-graduated scales Rules are 18" in length and .075" (1.9mm) thick [custom1] SPECIFICATIONS Material: Aluminum Blade Lengths (in): 18" Blade Widths (in): 1-1/8" Thickness (in): .075" Graduation Style: English Graduations: 1/8", 1/16" [/custom1]