Extensions must always remain invisible! This should also go for quick extensions. With GL Apps you can be sure that this is indeed the case.
Standard systems use the Sandwich Technique. This sounds a little bit like "thick", and not really like invisible. At Great Lengths we like to stay smart. And invisible, of course! We call our technique "Invisible Touch": Its effect is that your own hair is guaranteed to cover the extensions! Both above and below is your own hair. And in the middle: GL Apps. Very smart and definitely invisible, just like all the extensions from Great Lengths.