Whether an expert in the gym, a beginner to working out, or rehabilitating after an injury, ProSource Xtreme Power Resistance Bands are an effective form of heavy duty training that provide variety for your workouts and challenge your muscles in new ways. The colors indicate progressive resistance levels, ranging from 20 to 50 pounds, making them an excellent tool for those with more strength, especially when stacked. They allow you to work from different angles to involve more muscle groups, with a greater range of motion than with traditional weight machine exercises. Each tube band is 48 inches long and lightweight, designed to improve balance and coordination. Made from high-quality latex rubber, they are colored using the dipping method, which ensures durability and bands that will last, even with heavy use. A door anchor and convenient carrying bag enable you to workout from home or while traveling, so you can stay fit wherever life may take you.