Recall in seconds with 90% higher efficiency. The device emits ultraloud frequency sound waves with strong penetrating power to filter environmental noise, enabling your dog to instantly hear recall commands whether you are in a park, on a mountainside, or in the backyard. This helps eliminate ineffective calls and addresses recall problems. Precise frequency modulation for multidog training. It has an original rotary adjustment knob to easily set frequency tones. It matches the hearing sensitivity of different dogs and prevents instruction confusion. With just one whistle, you can train multiple dogs independently. Silent for human ears, worry training in any setting. The ultrasonic design is very quiet for humans, so training in apartments, communities, or at night does not disturb neighbors. You can strengthen your dog's behavior anytime and anywhere without pressure. Professionalgrade durability, rain or shine. Built to be sturdy and resistant to drops and bites. Waterproof design ensures consistent performance in rainy and snowy days, near rivers or seas, and even when exposed to dog saliva. Durable and longlasting, it is a reliable training partner. Practical use scenarios Outdoor recall during park visits, hikes, or backyard sessions. Training multiple dogs with a single whistle by using distinct tones for each dog. Quiet, discreet training in apartments, communities, or at night without disturbing others.