No material out there represents the dat, all you have to do is learn and know the materials being tested to your best ability, those product's out there for purchase have been of no use to me as I been exposed to the exam twice and method of question asked were mostly research type for sciences and qr filled with comparison were no material I used related to, don't at all depend on the product's on the market, if I were to take it again I wouldn't buy any of them, but retake not required for me.