Dog whistle for training dogs with ultrasonic sound, with a green case. - Brand: SPRINGER - Model: Dog Whistle - Case: Comes with a red plastic case - Frequency Range: Ultrasonic (40000Hz) Ultrasonic Dog Whistle: This whistle is designed to emit high-frequency sounds that are difficult for humans to hear, but audible to dogs. The SPRENGER dog whistle in the image is an ultrasonic type, and while it may sound like a breeze to humans, it emits a clear, high-pitched sound (40000Hz) that dogs can hear. It has a screw and nut to adjust the pitch, allowing you to fix the sound's height. When not in use, you can store it in the included cover to prevent dust and debris from entering. By rotating the body and lengthening the threaded part, you can change the pitch. A shorter threaded part produces a higher pitch, which can reach up to 360m depending on ambient noise and wind direction. Although it is new, it has been stored for a long time. Please refrain from purchasing if you are concerned about stains on the attached instructions or if you are overly sensitive.