INDUSTRY NINE A318 Stem - 50mm - BlackIndustry 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. The A318 utilizes a 31. 8mm handlebar clamp diameter providing 180 degrees of contact on the stem body for twist free security