1. This product is suitable for all models with air source devices. 2. The working current of the control relay must be 15A. 3. The -section of the main power line of the relay is or equal to 2.5mm. The output line is not less than 1.5mm. The negative (grounding) line should be in good contact to the use effect of this product. 4. The horn air source should be introduced directly from the air storage cylinder to achieve better sound quality: the air storage cylinder must be frequently discharged to avoid affecting the service life of the solenoid valve. 5. Working pressure 0.3-0.9MPa, optimal planting 0.42-0.68MPa. The temperature adaptation range is -40-80 Precautions for the use of solenoid valves: The air pipe joint of the solenoid valve should be tightened carefully. The filter screen may be blocked during use and should be cleaned frequently to avoid affecting the sound quality. Sound Pressure Level: 125db Colour:Red Material:Metal+ABS Package Contents: 5 * speakers Horns 1 * air pipe 1 * relay 1Set * installation accessories Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.