WaterRower Natural with S4 and WaterRower Mat. The WaterRower Natural Rowing Machine with S4 Monitor is hand crafted in solid Ash and stained Honey Oak for consistency of color. Each rowing machine has been hand finished with Danish Oil giving a deep luster and warmth to the wood. Wood has been chosen due to its marvelous engineering properties, primary amongst these is its ability to absorb sound and vibration enhancing the WaterRower’s smooth and quiet performance. The S4 Monitor has been designed with user friendliness in mind. It has been designed for easy QuickStart of most functions, simply press the on button and away you row. Delve a little deeper and there are many more advanced functions for the novice through the elite user. The WaterRower Mat provides traction for the most intense rowing sessions while protecting your floor from scuffs, scrapes, and sweat.