Ultrasound numbering device tip wear guide Use the 42-12 ultrasound numbering device tip wear guide to check if the numbering device tip needs replacement. 1. Tip wear will significantly reduce the effectiveness of the numbering device as it will affect the ultrasound frequencies. 2. The ferrite rod must be tight – a loose or broken rod will result in weak or no vibration. 3. A properly functioning tip at a power setting of 3-4 lights will contribute to producing cooling mist around the tip.