Proporcional caliper

Used either for rapid determination of percentages of flat and elongated particles in coarse aggregate fractions of 3/8″ (9.5 mm) or larger.

Consisting of 8″x16″ (203,2×406,4 mm) base plate with rubber feets, two fixed posts and a 12″ (305 mm) pivoting arm, allowing ratios of 1:2, 1:3, 1:4, 1:5 to be obtained.