Features: Made of waterproof plastic material with built-in scale, smaller and less prone to damage to easily rotating parts. This hovering flight computer can do everything the E6-B sliding chart type does, and can also use the wind side to solve true wind, true heading, wind in flight and speed problems. All prints are sandwiched between two pieces of plastic, so the numbers/prints will not be rubbed off during long-term use. This circular flight computer will help you solve a variety of calculations, such as flight planning, basic arithmetic or complex aviation calculations. Whether you are solving wind trigonometry problems, the calculator side can perform multiplication, division and unit conversion, and use scales to perform calculations for time, speed, distance, speed, fuel consumption, altitude. Specifications: Part Name: Flight Ruler Size: E6B-R2 4 inches / E6B-R 6 inches Material: Plastic Color: As shown in the picture Package Contents: 1 x Aviation Plotter Only the above package contents, other products are not included. Note: Light reflection and different monitors may cause the color of the item in the picture to be slightly different from the actual item. The allowed measurement error is +/- 1-3 cm.