If those extension tubes came with the telescope (they appear to be ES extension tubes), then they fit on your scope. You need to unscrew the collar from the back end of the focuser tube and then screw on one or two of these extensions. Then screw that collar back onto the end of the extension tube. Those are probably focuser extension tubes specifically for your focuser.
Explore Scientific iEXOS-100 and EXOS-2GT (non-PMC)
Explore Scientific ED 102mm Refractor