A Klaxon SS6. Note the lack of rainshield.
The ACA Sentry 95 was a short-lived siren that was made by ACA. The Sentry 95 is a rebrand of Klaxon Signals' SS6 siren (Early 1950s - 1970s), with the only difference between the two being the Sentry 95 having a rain shield. It is unknown whether or not this siren was ever produced in the first place.
The Sentry 95 is a very small siren, with a 5/6 port ratio and a range of 95db at 100ft. It was intended for small coverage gaps , and fire stations, but was so weak that nobody wanted them. It was introduced around 1968 alongside ACA's other sirens, and disappeared from the catalogue not long after. It's likely that it was discontinued very early on due to poor sales.
2 Klaxon SS6s are currently in private possession and are both in the UK.
One of these was an SS6 found rusted and broken at an abandoned factory in the UK. It is now in private possession and was originally installed in 1951 or 52!
The Sentry 95 is a rebrand of Klaxon Signal's SS6 siren, as ACA entered a partnership with Klaxon to allow ACA to rebrand and sell the SS6. The SS6 itself is very rare, with only 8 units in existence (3 in the UK and 5 in Australia). As of now, the Sentry 95 is extinct and no units survive to this day, if any were ever made in the first place. Not much else is known about this relatively obscure siren.