So you are looking for a sled to use indoors and outside to build a stronger body? The TANK All Surface Sled is worth a look. It is a handy tool for push and pull workouts. You can use it for CrossFit, HIIT training, and rehab. Resistance is applied with both directions to push your body.
You can select from 3 levels of resistance. TANK’s inflated soft wheels allow you to exercise without damaging your grass, hardwood, or carpet surface.