The flight ruler is a measuring tool designed compatible withthe aviation industry, mainly used to measure the height, width and thickness of (such as the of helicopters or aircraft). Scale design: The flight ruler is usually equipped with dense scales to the accuracy of the reading. Correct placement: The operator needs to firmly fix the flight ruler on the rotor to accurate reading. The measured value can be read directly through the scale, or it can be connected to a computer compatible withdigital processing. Note: Keep the flight ruler balanced to avoid errors caused by improper operation. 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 not be rubbed off during long-term use. This circular flight computer 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. Color: As Shown Material: plastic Package Contents: 1 * Flight Ruler(Only one) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.