It's molded plastic that keeps its shape exactly for the gun it was made for. As for which one...that is 100% a personal decision with size, fit, other materials like the back side being kydex or perhaps cowhide (hybrid holster), how it fits with YOUR body (same gun, same material yet one can print like a gal in spandex and the other is completely hidden).I'm interested.. what sets a kydex holster above other holsters? Any model or type of kydex, or a particular?
Buy one...see if it works for you (including comfort hours later). If not, return it and try something else.