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Class Information
Number: 181/19
Name: Acoustics > Speaking tubes > Alarms and indicators
Description: Alarms or indicators of a speaking-tube.

Patents under this class:

Patent Number Title Of Patent Date Issued
7525440 Person monitoring Apr. 28, 2009
5659157 7th order acoustic speaker Aug. 19, 1997
4825800 Marine horn installation May. 2, 1989
4669683 Moveable safety railing Jun. 2, 1987
4505358 Voice communicator Mar. 19, 1985

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