The E-4 Is a Small Industrial Siren by Sentry Siren..
On the Sentry Siren Website it Says:
For those looking for a powerful electronic siren in a compact package, Sentry Siren offers the E-4. This extra high output Siren, 113 db(A) (nominal), is highly effective where the ambient noise level is excessive. The Model E-4 features 32 distinctive sounds, which are selectable by manual switching as well as a priority sound override option. All 32 sounds can be obtained from a two wire supply. The E-4 is available in two versions, the E-4DC (9-30 VDC), or the E-4AC Sentry’s entry level electronic siren provides superior flexibility in industrial signalling, combined with the dependability that is our hallmark.