This ad was released roughly around 1948, advertising the Mobil Directo air raid siren. I’ve posted an ad for this siren previously, which only featured the Mobil Directo’s gas engine-driven BN52 model. This ad introduced a new variant of the Mobil-Directo, driven by a 10HP electric motor instead of the 25HP Wisconsin aircooled engine. This new electric model proved extremely successful, as engines require significantly more maintenance and are far less practical for siren use than a motor.

The new model, known as the Mobil Directo BN44E, saw widespread use across the United States and Canada. Rated at 126 dB @ 100ft for 10/12-port dual tone models to nearly 128 dB for 8-port single tone models, the BN44E was louder than most other sirens during the time of its production. The engine-driven BN52 would see sales dry up quickly after the BN44E’s release, being discontinued in 1953. The BN44E would be sold until 1967, when BNCO was forced to stop making sirens due to stiff competition from Federal Sign & Signal.

BNCO would create a new division, known as Alerting Communicators of America (ACA) who would redesign the Mobil Directo into the Allertor 125, which saw the steel projector replaced with a fiberglass projector, and the dual belt-driven pulleys on the rotation drive replaced by a single chain-drive rotation mechanism under the siren. The Allertor 125 would be sold until 1981, when it was replaced by the Penetrator-10 which replaced the large projector with a simplified horn.