This is the Kenwood KAC-M1814 4 Channel micro sized amplifier, which is fully weatherproof (using a conformal coated internal board to resist water/moisture).
Kenwood's super-compact KAC-M1814 will add new clarity and impact to the basic sound system of almost any kind of vehicle on land or water, and it'll fit in a lot of places when space is tight. This marine-rated 4-channel amp will pump up your audio system with 45 watts RMS per channel — that's more than twice the power of most car stereos or marine receivers. The amp uses plastic covers to protect its connections and features a conformal-coated circuit board that keeps out moisture and salt, so the party won't stop just because of a little wetness.
The KAC-M1814 will accept a signal from just about any source, whether you're using RCA cables from an aftermarket receiver or speaker wires from a factory radio. When you use the speaker-level inputs, the amplifier will sense the signal and turn itself on, so you won't need to run a separate remote turn-on lead to the receiver or fuse box. Kenwood goes to great lengths to ensure good sound quality, putting the pre-amp and output power amp stages on separate circuit boards for better, cleaner performance.