I have been using this type of countersink for over 20 years. Used this bit on plain soft pine and the cheap metal cracked and broke. Not nearly as good as other countersinks from other companies.
Just bought these after reading a tool review for use on two 5/4 Ipe decks. We replaced a couple of Fuller countersinks and this one laid almost 1,000 square feet of deck and still cuts well. Worth the price.