Golf clubs with offset have a face that is set slightly behind the hosel, a design that gives golfers an extra split-second to square the clubface before impact. In a set with progressive offset, the amount of offset gradually decreases as the clubs become shorter. For example, the 5-iron has a bit less offset than the 4-iron.
Progressive offset accounts for the fact that longer clubs are more difficult to swing into a square impact position, whereas most golfers have little trouble doing so with the short irons. Matching sets of woods, hybrids and irons may be built with progressive offset.