1.Spread the measure and raise the transparent flap vertically.2.Place the tip of the fish on the flap and measure.(The flap wall is designed to be at 0 cm.)A compact tape measure that uses a highly water-repellent, high-strength tarpaulin material and is convenient to carry.When stored: Approx. 65 mm (W) x Approx. 200 mm (H) x Approx. 20 mm (D)