The ZET-Horn essentially consists of a piston inside a cylinder driven by an AC 3-phase motor and a joining sound horn. The piston oscillates at a certain frequency making the air inside the sound projector vibrate in resonance to produce a clean sound audible over a wide range. Higher amplitudes of the harmonics ensure best possible penetration of the normal background noise level on board. The ZET-Horn has a run-up time of less than 0.15 seconds which guarantees a pure, concentrated sound with best directional properties.

The Makrofon is a compressed air powered diaphragm sound transmitter. It is most commonly installed on board of all types of vessels, as well as on rail vehicles. Makrofons are reliable whistles distinguished by their low air consumption, strong sound intensity and wide range of audibility. Due to the simple and solid design, Makrofons are practically maintenance-free. The diaphragm housings are made of reliable materials, seawater resistant plastic is used for the protective cover only. For vessels the sound frequencies of Makrofons range between 90 Hz and 370 Hz and go up to 660 Hz for rail vehicles and may exceed 1000 Hz for alarm purposes.

The ZETFON is an electronic sound transmitter. It consists of the ZETFON (sound emitter) itself mounted on the mast and a control and amplifier unit for wheelhouse installation. The control and amplifier unit contains all electronic components including the heavy transformer. This way heavy weight on the mast is avoided and vital components are within easy reach. The ZETFON is an economic alternative to air whistles on small vessels without air compressor.