The single knot is the most basic type of knots. As the name suggests, it is a simple knot tied on the base, usually with one or more hairs tied to each knot.Since this knot is only tied once, it will fall off more easily than other methods, and this knot will keep the hair flat to the scalp and in one direction, so it is usually not used on the front or top area， but on the side or back.And because the knot is small, it makes the hair system look more natural and less visible.
Double knots technique is knotting twice on the base,so it will provide more durable than single knots.The disadvantage is double knots will make the dots at the bottom bigger and more detectable.So it also can`t be used at the front or top area.
Single reverse split knots
Single reverse split knots are mainly used on poly skin base materials.If a hair system come with PU perimeter ,they always use single reverse split knots technique. The hair is knotted half on one side and half on the other side of the hole. So it can provide more durable than single knots and less visible than double knots.Also it can be combed in many direction.
Double reverse split knots
Double reverse split knots like the name shows it is tied twice of single split knots.This knot is commonly used in the top and back of systems to provide that extra volume and movement. Because of its bigger knots on the bottom,it`s more visible than single split knots.