Each strand weight 0.75g has approx 180 individual hairs that are bonded together on the ends by a keratin protein glue shape of Nail shape hair that is melted by a fusion iron or fusion iron or fusion heat wand which connected to individual section of your hair. Since these 100% human sleek hair has been cuticle aligned to ensure less tangling and durability , you can wash, dry and style just like your own hair. You may also curl, flat ironed or even color that hair. It can take anywhere from 150-250 strands for a full head of hair depending on how thick your own hair is. They last approx 3-4 months before they need to take out and redo again.NOTE: The body wave wavy texture will loosen once washed and will dry semi straight with body. You can use a curling iron or hot rollers for a few minutes and they will once again have beautiful waves with lots of bounce. Chemical process like coloring, tinting or perm can drastically change the surface of the hair, thus stressing it. You should only let authorized professional perform such services in order to get the most out of your extension hair.