JIM-GEM Wheeler Pentaprism Caliper

Measure from any unobstructed sighting position and at any height on the tree-stump, dbh or merchantable height. Two pentaprisms, mounted in a tubular metal frame, permit simultaneous viewing along parallel lines of sight. The prism on the left side is fixed while the right prism is movable along the measuring scale. The image of the right side of the stem as viewed through both prisms can be aligned with the left side. At the alignment position, the outside bark diameter of the stem may be read directly from the measuring scale. Measures diameters 3” to 24” or 7 cm to 62 cm. Accurate to ±0.1 inch; ±2 mm at 50 feet.