The WaterRower is considered by many to be the best rower currently available on the market.The Natural in Ash (S4) adds performance electronics to WaterRowers beauty and renowned water resistance. It features WaterRowers patented water flywheel technology, which produces an unbeatable simulation of real-life, on-the-water rowing. Like all WaterRowers, the Natural in Ash (S4) is extremely quiet and aesthetically designed to complement high-end homes. The S4 performance monitor has six information and programming windows, six QuickSelection buttons, and three navigation buttons. It displays workout intensity, stroke rate, heart rate, zone bar, duration, and distance. Pair it with the optional WaterRower heart rate receiver to add a great dimension to your training!Water resistance acts like real rowing: the faster you pull, the more difficult it gets. You can also adjust the resistance in your WaterRower by changing the level of water in the tank (the more water, the harder the workout). Series 4 Performance Monitor The Series 4 Performance Monitor has been designed to balance technical sophistication with user-friendliness. The monitor has six information and programming windows, six QuickSelection buttons, and three navigation buttons. It displays workout intensity, stroke rate, heart rate, zone bar, duration, and distance. Compatible with the optional WaterRower Heart Rate Chest Strap and Receiver, the Series 4 Performance Monitor will allow you to optimize your workout, achieve your exercise objectives, and encourage you to exercise regularly. Stylish Design The Natural in Ash (S4) is designed for equally gorgeous look and performance. Every detail complements the overall aesthetic and performance of this unparalleled machine. Built in America, the Natural in Ash (S4) is a product of modern European design. It's hand-crafted in solid ash and stained honey oak for consistency of color.