Each strand weight 0.75g and has approx 180 individual hairs that are bonded together on the ends by a keratin protein glue of I shape hair that is... THE SHOELACE / NEEDLE TIP AND THIS HAIR CAN BE USED WITH THE MICRO LINKS, RINGS, BEADS, TUBES AND SHRINKIES .... 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 be taken out and redone again.