Just so you know everything is a jpg but the mane is the only one that says a .png. Unless you are using a different eye effect.
It really all depends on what coding you have inputed in your notebook. Sometimes you can use all your items as png, just cause of the coding. But usually when you are using .pngs, it cause you don't want something to show. Which is why .Pngs are the best when using a Transparent coding.
But for plain and simple presets, they are all jpg except the mane.
NOTE: To also add wings, you must save them as jgps too. Such as this...
preset_4equipMatR