SunRace originated in Taiwan in 1972, initially providing entry-level products particularly to North and South America. The boom in sales of... SunRace Mountain Bike Rear Derailleur alloy extended link (SP570) for use with ultra wide ratio cassettes. Provides the extra clearance required by the derailleur to clear the latest low ratio cassettes (42 tooth plus). Made of 7075 Alloy. Durable black anodized finish.