The invention relates to a method for increasing hair volume or length or adding a different color, including the steps of providing a plurality of extensions comprising several hairs, which are connected by a fixing element, the extensions being aligned and substantially in parallel with their fixing elements located on a support tape having an adhesive face, adhering the adhesive face of the support tape to head hair and positioning the extensions, and connecting the extensions with the head hair by attaching the fixing elements to it Further, the invention relates to an assembly and system for use in such method.