Industry Nine A318 Stem - 50mm 31.8mm Clamp +/-4.4 1 1/8" Aluminum Bronze. Industry Nines A-Series mountain bike stems are crafted from domestically-sourced 7075 aluminum billet into a svelte design achieving a nexus of form and function. Using advanced manufacturing techniques honed over decades in their CNC machine shop they continue their tradition of offering riders uncompromising components.