Digital technology and single molectron make, performance steady and reliable. Built in LID display, sound amplifying, small size, great big sound. Notice: No instructions attached, please make sure you know the install and connection methods before you buy it. The voltage is AC 220V, US should buy another voltage transformer(here is not included), to make sure the item can working successfully in your area. Package Content : 2 x Mini Motor Siren Only the above package content, other products are not included. Note: Light 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.