This 42g 1 Barb needle is very stable is the best needle for the Directional Mono Rooting . For the conventional technique ( placing a lock of hair and prick ) this needle is less suitable , since the barb is only on one side of the needle. With proper use, this needle pulls just one hair into the vinyl. This needle 's position must be checked and the edge of the triangular shaft with the barb, must be facing the vinyl ! Because only one edge has a barb, it causes only a minute slit in the vinyl, but are hidden under the hair and therefore damages the vinyl the least.