Improves power and efrience and two and four stroke engines. Great for all Yamaha boats, ATVs, outboards, waverunners, power products, generators, pressure washers, SxS, golf aarts & more.kit includes 1 - ACC-RNGFR-PL-12 ring free plus fuel additive & 1- ACC-FSTAB-PL-12 fuel stabilizer plus.