A tolerance ring configured to improve mass eccentricity of an actuator arm assembly. Multiple contacts are fixed in the insulative housing and include a number of soldering tails under an arrangement that each adjacent two soldering tails are separated by one of the ribs. A list associating the reference image frame with information specifying the corresponding reference image data file is generated with a content information list generating unit. A guard structure is installed in the slit of the locating pin to isolate the interior of the post member from the interior of the slit while permitting the axial movement of the clamp arm in the slit. Corresponding methods, systems, apparatuses, and computer-readable media are also described. The VCC and GND power lines of the USB port and the twisted paired signal lines of D and D are connected with the corresponding terminals on a parallel port so as to test the connection between the USB port and the USB host controller.