A 4516 is pretty big for an IWB holster, but I would venture a guess that most holsters that fit midsize Sigs and HK's would fit a 4516. You may have to take it to your local gun store and test fit a few. As far as the CS9 and CS45 IWB holsters, again subcompact Sig, HK, Glock and possibly Kahrs would fit. Again i would recommend a test fit. DeSantis makes great IWB holsters and offers numerous models.