The shinfin fins teach a horizontal body position and good streamlined kick. The trick is to relax and let the fins flow naturally. The fins have a “natural resonance”, so you can just let the fins guide you without thinking about it. I’ve witnessed this with children with CP – swimming on their front and back – it can be almost instantaneous and very dramatic to watch. Also, the fin “natural resonance” kick pattern tends to hold for a while even after they take the fins off – people remember the feel of the kick.