From the manufacturer's website:

306 Series - Mini Reflex 6 Watt Horn

Compact horn speaker is ideal for limited space page and talkback applications. Driver is a special design 3-1/2" cone speaker. Adjustable base or flange mount. Vehicle mount with K4DM bracket kit.

Product Technical Specifications

• For paging and music in moderately noisy environments.
• Power rating 6 watts, continuous duty.
• Reflex driver uses moisture resistant diaphragm.
• Pleasing voice projection – high speech intelligibility.
• Weather and corrosion resistant construction of impact & UV resistant ABS and stainless steel fasteners.
• Adjustable mounting base will attach to a 3-inch electrical box.
• May be recess mounted – hole locations on flange.
• Attractive tan color. Also available in black.
• Enclosed transformer models tapped with 5-conductor color coded cable.
• Manufactured in Fourjay's plant under strict quality requirements.

Specifications Sheet