Use as a replacement blade and coil spring or for new installations. The SmartTrack Foil rudder blade is revolutionary in the field of rudders. Using a foil design, it induces 25% less drag and 32% more turning efficiency than an ordinary flat aluminum blade. It looks faster because it is faster! The molded rudder blade is foil shaped so water moves across with less turbulence. Compared to an ordinary flat aluminum blade, this design reduces drag and significantly increases turning efficiency. When not in use, its slim profile also exposes less surface area to crosswind drag. This rudder blade is also a QCC Skeg Blade, found in some, but not all QCC kayaks (contact us us for info on cable). You will need a stainless steel bike cable for it. The SmartTrack rudder blade is available in two sizes for single (13.5 in.) and tandem (16.75 in.) kayaks, and a short (11 in.). The rudder blade size is a personal choice. A tandem size blade may be more suited to kayaks with a high stern deck, some sit-on-tops and for sailing some kayaks. This is the best possible way to get a replacement Smart Track Coil Spring. The blade comes with the coil spring.