they're just meshes, they don't really show up as clothes until your sim is pregnant. these show up as clothes because they have the belly mesh, they're not imported into the inteenimater package like the meshes are
okay download this sim! i created it so it's by my account since i couldn't find the origional model..plus i'm kinda lazy and i didnt' feel like searching lmao! and i felt like making a simtype self of my guy friend, jason