Torque TANK M4 All-Surface SledThe Torque TANK M4 is unlike anything else out there literally. An All Surface Sled featuring a DOUBLE braking system that adds resistance to any push, but without scarring your floor with abrasive metal pads. It's a safe, effective, and brand new way to get a sled workout in your facility. For the single brake system, check out the TANK M2. With the M4, you won't need to add extra plates to up the resistance. It's even configurable with the Group