My brother has a set of old maybe 1988 Titleist DTR irons in good shape. He was missing the sand wedge and found one used online so ordered it to complete the set. All of the clubs he's had have a red dot on the club head. The sand wedge we ordered does not have the red dot, but other than that it looks exactly the same as the others. Does anyone know what this red dot means? Thanks ! Just curious.