Ultrasonic Punch Horn by Sharpertek. Ultrasonic Punch Diameter 2 3/4" Titanium with either Chrome or Carbide coating options. Ultrasonic punch frequency is 20KHZ With Blow Off feature. Blow off feature connects the horn to a 1/16 NPT push to connect fitting used to blow off the punched disk out of the horn. Part Number: HP-2 3/4-20KHZ-TI-BO-TI. Other shapes such as square and oval are available upon request.