Industry Nine A318 Stem – 50mm 31.8mm Clamp + -4.4 1 1 8 Aluminum Purple. Industry Nine 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 our CNC machine shop we continue our proud tradition of offering riders uncompromising components. The A35 and A318 utilize either a 35mm or 31.8mm handlebar clamp diameter providing 180 degrees of contact on the stem body for twist-free security that will play nice with both alloy and carbon bars. Stainless steel hardware ensures everything stays in place and looks great regardless of mud-blasting washes or rainforest climates.