The BST-Asymmetric rim design of the Crest MK4 allows for a stronger wheel while offering the easy inflation and Stan s trademark unmatched airtight seal. The Crest MK4 rim is optimized for 40mm Gravel tires and up to 2.3 mountain tires; making it a great; versatile choice for a wide range of bikes and riding styles.The durable but forgiving ride of the Crest MK4�s 6069 alloy construction and lightweight, low-profile rim shape offer an unbeatable ride quality uniquely suited to Gravel and short-travel XC riding, and like all rims that bear the Crest name, it�s built f25mm rim width optimized for Gravel and XC tires up to 2.3�Light and durable 6069 aluminum with welded joint and reinforced spoke bedBST-Asymmetric design combines Stan�s legendary easy tubeless inflation with a stronger, more balanced wheel build3-year rim warranty with 1-year crash replacement---