1.4mm wall straight-gauge 4130 chromoly arms with concentric taper One-pieced forged and broached spindle boss with two tuck pin holes Drilled and machined 9/16-inch pedal boss with TIG-welded gusset Left-hand and right-hand drive compatible Hollow heat-treated 4130 chromoly 48-spline / 19MM spindle Grade-8 center bolts and tuck pin hardware Works with Spanish, Mid, Euro bottom brackets (bottom bracket sold separately) Weight: 842g (1 lb. 13.5 oz.)