[Specification] length: 45mm diameter: 8mm, key ring diameter 2.4CM
Here’s the common whistle language:
● short tone ( within one second ); ■ long sound ( more than 3 seconds );
The whistle interval between instructions is 2 to 3 seconds, and the interval between instructions is more than 30 seconds (for example, the interval between repeating instructions is more than 30 seconds).
Collect (two short and long) to the direction of whistle sound.
* (a short and long)start and speed up;
Low ■ one short and two long ) someone left behind, the former team waiting for the latter team;
* (three short) encountered difficulties to seek help.
[three short three long three short) this is the international common SOS code.