1. This product is suitable for all models with air source device. 2. The operating current of the control relay must be 10A. 3. The -section of the main power line of the relay is or equal to 2.5MM2. The output line is not less than 1.5MM2. The negative (ground) line should be in good contact to the use of this product. 4. The air source of the horn should be introduced directly from the Air reservoir tank to achieve better sound quality: the Air reservoir tank must often Drain moisture to affect the service life of the solenoid valve. 5. Working pressure 0.3~0.9MPa, Optimal Working pressure0.42~0.68MPa. The temperature adaptation range is -40~80℃ Sound level: 120±0.5db Precautions for the use of solenoid valves: The air pipe joint of the solenoid valve should be carefully tightened. The filter screen sometimes be blocked during use, so it should be cleaned frequently so as not to affect the sound quality. Colour:black Material:ABS+metal Package Contents: 2x Air Horn 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.