Purchased 10 of these to use during strength and condition sessions for JROTC cadets and for our Raider competitions. I left the skids on a few for use on asphalt and took them off the rest for use on our grass field. We have used them empty and up to 290# of weight with no variance in performance. We push, pull and have tandem teams push/pull simultaneously depending on what I can dream up. These sleds are very heartily built and have withstood everything a bunch of teens can put them through. Definitely recommend these for any type of sled workouts you come up with.