No 'silent' dog whistle is truly silent. If it were, nothing would be able to hear it! The word ‘silent’ is written in inverted commas because you can hear it, BUT only just. What your dog hears is really loud and travels up to 1.5km. Adjustable through a wide range of frequencies using a screw piston mechanism enabling you to tune it to suit your own dog, this is the most versatile silent dog whistle that can be used with all breeds. A booklet is supplied with each one giving easy instructions on adjusting the whistle and training your dog. It is designed with special air directors to tightly control the frequency produced and generates over a mile of sound with minimal effort. This is the ultimate silent dog training whistle.ACME ‘s popular range of various pitched dog training whistles suitable for all type of dogs and the most popular choice for shooters and triallers alike.