Torque TANK M4 Push Sled – Magnetic Resistance Sled for Indoor & Outdoor Training | Fitness Specialist TXTorque TANK M4 Push Sled All Surface Resistance Training The Torque TANK M4 redefines sled training with a patented resistance system that increases with speed. Built for indoor and outdoor use, it allows athletes to train on nearly any surface without damage, making it ideal for gyms, performance centers, and tactical strength training. This non motorized, self powered sled eliminates the need for additional weight plates. With three adjustable