The Cane Creek Hellbender 70 Slam IS42 / IS52 4.6mm is a top-of-the-line headset for cyclists who want to lower their handlebars without sacrificing bearing longevity and proper preload. With its low stack height bearing cover options, premium stainless steel Hellbender bearing, and 6061 T-6 Aluminum cups and covers, this headset is designed to provide maximum strength and minimal weight.The cups and covers of the Hellbender 70 Slam are made from durable 6061 T-6 Aluminum, which is internally contoured and relieved to reduce weight while maintaining strength. The top cover is specifically designed to have the lowest stack height possible for both ZS and IS headsets.The alloy dual-seal crown race of the Hellbender 70 Slam ensures excellent seal efficiency, while the low friction carbon-friendly captured compression ring further enhances performance. Premium sealed HELLBENDER stainless bearings provide smooth and reliable operation.Compared to normal ZS Hellbender headsets, the stack height of the Hellbender 70 Slam is reduced. For ZS headsets, the top stack height is only 2mm (compared to 8mm for normal ZS Hellbenders), and for IS headsets, the top stack height is 4.6mm (compared to 9mm for normal ZS Hellbenders).Overall, the Cane Creek Hellbender 70 Slam IS42 / IS52 4.6mm is the perfect choice for cyclists looking to achieve a low handlebar position while maintaining exceptional performance and durability.