Mitsubishi Diamana 6th Gen RB Golf Shaft Driving Iron Designed to mimic the loft Designed to mimic the loft look and hand feel the Liberty Lines headcover lineup brings the collection's Americana story to every club in your bag High modulus 46 ton fiber in angle plies to lower torque without increasing weight Diamana™ RB (Red Board) – the third profile in the most recent generation – is designed with all the traditional branding that made Diamana™ so beloved – including a return to the original 53 63 73 83 weight class designations – and all the engineering prowess and material innovation that made the brand dominant on tour