The underwater-coatings specialists at Propspeed have partnered with transducer-maker Airmar Technologies to create Foulfree, a foul-release coating designed specifically for transducers. Foulfree combats marine growth to keep your electronics transducer clean and to streamline water flow, allowing your fish finder to perform optimally. Propspeed says the coating is biocide free and forms a super-slippery surface over the transducer; it lasts a minimum of 12 months. Foulfree comes in a 15 milliliter tube with an applicator brush, abrasive pad and clean wipe. It costs $39.99.