The Dynamixel AX-18A Smart Serial Servo from Robotis is a step up from the AX-12A servo providing twice the speed and 15% more torque. The AX-18A has additional feedback information such as speed, temperature, position and load. The Robotis AX servo product line features a simple, and robust, TTL level communication protocol. Over a single TTL signal line you can daisy chain several servos and position of several servos independently and read back their positions.
From Robotis, the CM-2+ is the controller board used to control the Dynamixel DX-series, RX-series servos that support RS-485 and AX-series servos which support TTL level.
The Dynamixel AX-12A Smart Serial Servo from Robotis is the most advanced actuator on the market in this price range and has become the defacto standard for the next generation of hobby robotics.
Use these roll pins to fix sprockets to a shaft and keep them locked in place.