Saved RENDERS are image files. In whatever format you chose to save them in. Like PNG (I think that's the default) - Poser can't open pictures, you'll need an image viewer for that.

 

If you mean PZ3s, Poser should be able to open those.

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.