清脆响亮的双音口哨，双音声音穿透力更强，最高可超120dB。可用于比赛裁判用哨或者户外求生用哨。

便于打印，无需支撑。

A loud two-tone whistle,used for sporting events to emergency signaling,producing an impressive ≥120 dB sound.Easy to 3d print without support.