I had one that had two straps that was to be tied about three or four feet up the trunk and then a canvas seat that was free hanging. do not remember the name. It was a real hip wedge, so a fit a piece of plywood in it and added a butt pad that I could clip to my belt. I still have the butt pad, but the sling has long been stolen, like almost everything else that I ever leave over night in our public woods. I have found the the Nifty Seat with the long stake and my butt pad to be more comfortable and more versatile, easy to carry assembled with just nylon web belt around my waist, that goes through the seat frame and around the stake, quiet to set up, and very steady if I have something to lean against. I have also found that the Grizzly strap on seat very easy to use, but I do make a bit of noise when ratcheting the belt tight.
A newer one that I believe is still around is called ez hunter sitdrag.