Celt Sport Alloy Downhill Mountain / BMX Bike Stem - 45mm x 31.8mm Weight: 120g 31.8 Bar Bore, 1 1/8 Steerer Clamp, 45mm Stack Height AL6061 T6 3D Forged With Post CNC CNC Center Bore To Reduce Weight Four Bolt Bar Clamp Holds Bar Securely in Position