can handle heavy hair but tips and edges too sharp [SEP] these are stand ins when i cannot have metal in my hair for whatever reason they flex more than i like but they are plastic i find the tips to be too sharp for comfort i have to use caution when turning or pushing so my buns are not always as tight as needed for activity also the teeth edges are sharp as well cut my hair i have had to sand down the edges hence the stars more care toward finishing is needed recommend with reservations