The WidowX Robot Arm Mark II is the update to Interbotix Labs' entry level arm offering for the MX series of DYNAMIXEL Servos. The Mark II has a few improvements that we've made based upon our own testing as well as customer feedback. We've upgraded the elbow servo from an MX-28 to an MX-64 complete with custom aluminum brackets for added frame strength, replaced the Arbotix with the new Arbotix-M, and streamlined the arm structure to be lighter, simpler, and stronger. The MX series actuators provide a full 360 degree freedom of movement in the base, ultra-high resolution of 4096 positions, user-definable PID parameters, and extremely smooth interpolation. The hefty MX-64 shoulder & elbow servos gives the WidowX very strong lifting strength in a slim frame. If you are looking for medium lifting strength and desire smooth control, high accuracy and repeat-ability the WidowX is a great mid-level arm choice.