Get a top-quality product for a top-quality workout. The Smart Obsidian Surge 500 Water Rowing Machine will keep your workouts engaging and challenging. Studies have indicated rowing can work up to 85% of the body’s muscular system without the joint impact of other conventional cardio exercises. This in turn results in higher calorie expenditure in a shorter period of time. Elevate your workout and be more efficient with the Obsidian Surge 500 Water Rowing Machine.