Yacker Tracker- Self-Monitoring Sound Meter Finally- you select the appropriate level of noise for any given situation! Traffic light is computerized with adjustable sound level meter which can be set from 40 dB to 120 dB. Green light stays lit until noise in room goes above set level- then a flashing yellow light comes on as a warning. When sound level reaches 20 decibels above set level- a red light and siren sound come on (siren sound is optional). Lights can also be adjusted manually. Unit is 18" tall and can stand on its own or be mounted on the wall. AC powered. WARNING: Choking Hazard - Small Parts. Not for Children under 3 yrs.