3t ionic 25 pro setback alloy seatpostionicis a new seatpost design featuring the sophisticated and robust 3texclusive difflock seat clamp ionic25 places the seat clamp assembly 25mm behind the seatposts centerline this gives athletes the option of a more rearward position on todays shorter framesets the splined alloy difflock coupling is a highly accurate method of setting saddle angle needing only lightweight clamping by side mounted bolts it is especially useful for fine adjustment o