The Sonic TM275LH-W is a urethane, transom mounted CHIRP transducer, ideal for vessels 22 ft and up. This dual band transducer combines low CHIRP frequencies to accurately track bottom in deep water. High CHIRP affords best resolution in the upper water column and in shallower depths.
This transducer was only in the water for 6 weeks. I does show some slight signs of use in salt water. However, it functions perfectly. List price on this transducer was $2390.