Be careful what you buy. There are in particular 50 and 500 denomination Qatari Riyals which are fake and these machines cannot detect them. Qatar Central Bank has been imposing a fine on each case of forged note, it not previously detected. After a resulting uproar, the machine supplier took back all the old machines and has supplied the market with the latest. Be careful that someone does not palm off an old useless machine to you.