The combination of blue flashing light and a two tone siren in one unit is called a blue light case. This system can be attached to any vehicle. So in emergency situations, you can use any vehicle as a priority vehicle by using a blue light case.
The combination of blue flashing lights and a two-tone siren is called a blue light case, because these optical and audible signals are housed in one unit. This can be attached by vacuum to the roof of your vehicle. This allows optical and acoustic signals to be attached when needed, rather than being built into a vehicle as standard. The tweet-tone-siren is used to emit an acoustic signal to warn traffic on the road in emergency situations. Blue-swinging-light with LED illumination is used in conjunction with a two-tone siren, to provide a distinctive signal with both sound and light.