"The SMI Aluminum Shellfish Gauge provides quick and accurate measurements of your catch. Features a stamped aluminum construction with laser-etched markings, and includes the following notches for common shellfish measurements: 5-3/4"", 6"" and 6-1/4"" crab measurements, 1-1/2"" clam measurement and 1-3/16"" shrimp carapace measurement. Always check your local shellfish and fishing regulations before taking to the water. Stamped aluminum construction Laser-etched markings Includes notchings for measurements"