DuraTrax Aluminum Servo Arm Single Blue FEATURES: Aluminum construction anodized blue in color Three plastic adapters allow horn to be used with Futaba JR KO Propo Airtronics/Sanwa Hitec Tower Hobbies and Hobbico brand servos One large and one small diameter linkage holes;INCLUDES: One Blue Duratrax Single Arm Servo Arm with three plastic adapters;REQUIRES: Fastening to servo shaft