Light As AERLong recognized as the world’s lightest headset, the AER series offers a hybrid steel and aluminum bearing that provides even greater durability and a 35% weight savings over comparable models. Strategic machining and precision contours provide an optimal balance between weight savings and strength.The new AER headset is the ideal headset choice for lightweight road and mountain bike applications. For an ultralight race day application, riders can outfit the AER with a Norglide® composite bearing.CNC-Machined 7075 T-6 alloy. Contoured and relieved to provide an optimal balance of weight and strengthStack Heights: 9mm (Short), 15mm (Tall)