number of directions for example the track ball component 802 may scroll in a single direction or in the reverse of that direction in other implementations the tracking device 104 can include a trackball component 804 that has multiple functions for example the track ball component may scroll in multiple directions and a user may press the trackball component 804 to make selections of objects displayed in a user interface in other implementations the tracking device 104 can include a scrolling mechanism 806 that can scroll and be oriented in multiple directions the position of the scrolling mechanism 806 can be maintained after adjustment by applying resistance supplied by a movement limiting mechanism such as a set of splines surrounding the scrolling mechanism 804 for example the user can adjust the scrolling mechanism 806 to a position that is a comfortable scrolling position for the user the resistance of the splines prevents the scrolling mechanism 806 from slipping from that position fig9 is a schematic diagram showing an implementation of a base 902 where a tracking device is received at a frontal portion of the base 902 in an exemplary implementation the tracking device 904 can be configured to protrude partially outside the front of the base 902 to allow the user 39 s finger quick access for removal from the base 902 in another implementation the base 902 may include other components that require the components be located in the middle or back locations of the base 902 for example the base 902 may include tracking mechanism components that occupy the space in the middle and back locations of the base 902 in some implementations if the user.