Executive summary: Do the House of Staunton Zagreb '59 Series chess pieces meet the rules for standard equipment? (This set is also available from USCF sales.) The issue is that the bishops and queens have knobs at the top of opposite colors (a black knob on the white pieces, and a white knob on the black pieces). The same is true of the king’s cross.
I had to deal with a claim recently that the set is not standard equipment. Although I did not have access to a copy of the fourth edition of the rule book at the tournament, I remembered there was text in the rule that was removed for the fifth edition. However, based on the text of the current edition, I ruled that the set is standard equipment.
History: In the third edition of the rule book, on page 128, under “Form,” the last sentence reads: “The bishop’s top may have an angled groove or a knob of a different color to distinguish it from a pawn.” That changed in the fourth edition; rule 40C on pages 165-166 clearly states: “If the bishop’s top has a knob of a different color, the set is nonstandard.” This sentence was removed in the fifth edition.