plus distance 84 between the center of the radial outer surface 76 and the center of bore 80 of bearing 74 fig9 and 10 distance 164 is equal to the difference between outer diameter 62 of outer tube 52 and outer diameter 117 of element 116 less distance 84 between the center of the radial outer surface 76 and the center of bore 80 of bearing 74 fig9 and 10 decreasing distance 164 increases the surgeon 39 s view of the burr during use and increases the ability of the burr to access structures during use referring further to fig2 during use debris is aspirated from the site along two paths which join in lumen 115 of inner tube 104 from which the debris is removed via aspiration passage 123 in inner hub 124 see fig2 by suction supplied by the handpiece debris in close proximity to burr head 116 follows path 170 through passage 168 formed by groves 90 in bearing 74 fig9 and 10 to aspiration port 111 in inner tube 104 debris in the liquid in proximity to distal end 56 of outer tube 52 is aspirated along path 172 via slots 73 to aspiration port 111 in inner tube 104 because the abrading element of abrader 160 is not concentrically positioned within the outer tube but is displaced away from the hood the diameter of the abrading element can be increased and still maintain the minimum clearance required between the element and the hood this allows the use of a larger abrading element for a given outer tube diameter than would be possible if the.