The first two cams I got have threaded holes in bottoms and have what looks like screw in tree steps w/ threaded rod on top. The 2nd pair only have the strap mounting system. I got two tree steps at Mal-Wart and had bolts welded on ends. I then took coupling nuts and pieces of threaded rod and epoxied them on camera back because I liked the versatility of 1st mounting system. Haven't pulled any cards on the new ones yet to see how they work. I used the two nuts/threaded rod for more surface area for glue on cam backs.