Wildco Gravelometer Field Sieve.

This handheld device - also known as a gravel template and pebble meter - is used to grade or measure gravel and small cobble-sized bed sediments in the field. Constructed of 1/8" aluminum, it has 14 square holes of common sieve sizes (1/2-phi unit classes) ranging from 2 mm to 180 mm. Scale (in 10 mm increments) along one side can be used to measure up to 310 mm. 13.5 x 11" (342.9 mm x 279.4 mm). Wt. 0.62 lbs. (1.4 kg).