Gravity training sled Kwell Sled is a functional training sled designed for those who want to practice “resistance training” - a practice that consists of pulling a mass using only body strength. This training method helps to improve some specific capabilities, such as strength, explosiveness, reactivity and endurance. Two functions make these sled unique and innovative: they are soft and can be loaded with traditional functional heavy bags. This very new instrument can be easily stored by folding in the same way as a carpet, loaded with one to five bags, and has a sliding surface suitable for rubber floors of the newest functional training areas.