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Class Information
Number: 181/
Name: Acoustics > Speaking tubes

Sub-classes under this class:

Class Number Class Name Patents
181/19 Alarms and indicators 5
181/20 Combined mouth and ear pieces 13
181/21 Mouthpieces 17
181/18 Systems 12
181/22 Tubes 17

Patents under this class:

Patent Number Title Of Patent Date Issued

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