Hate to say but I do agree with this "ghastly guest" profibre is useless.
So is human hair! Is this guest a hair dresser or a cheap jumped up product company?
Whoever you are you should be thrown out of our industry and off this forum.I apologise on behalf of this rude,ignorant person.Let me assure you clients out there,thank goodness there are few idiots like this within our industry.Only at the very tacky end either ripping off consumers ,or a rip off merchant trying to make a buck out of professional people.IGNORE IT.
Also someone who has no knowledge of hair extensions,so don't listen,in fact you can see not to take any "advice" it's trying to give.