The keel cooler condenser fitting has two copper tubes projecting from it: they are connected together through a cupric-nickel loop that is cast into the sintered bronze. This version has a universal long thread for use on non-metallic boats. It is fitted with zinc anodes. 

Keel Coolers are available with or without sacrificial zincs, and a “Z” is added to the Part Number of the model with zincs to distinguish between the two. In the “Z” models there are two, circular zincs that are recessed into the bottom of the Keel Cooler, flush with the surface, and these do not affect performance. It is a requirement of the installation that an electrical connection is made between the Keel Cooler and the battery negative. In satisfying this requirement, the Keel Cooler is often connected electrically to the boats’ sacrificial zinc that is protecting the other underwater metal fittings. If this is found to be the case, a Keel Cooler with zincs is not necessary. If a “Z” model is used in a situation where zincs are not required, it may result in excessive zinc loss from the Keel Cooler zincs, as these will tend to take over the job previously performed by the boats’ zinc.   If the boat does not have a bonding system and/or employs non‐metallic underwater fittings it would be advisable to use a Keel Cooler with zincs as a safety precaution.  Ultimately the choice of whether to use a Keel Cooler with or without zincs rests with the purchaser. If in doubt, consult a marine corrosion specialist.

(Note picture may vary from actual item)