use the reduction tower 900 to provisionally lock the bone screw assembly 10 orientation without using a closure member to provisionally lock the bone screw assembly 10 for example the clinician positions the open unlocked distal end 907 of the reduction tower 900 adjacent and generally concentric to the receiver assembly 12 of the spinal anchor assembly 10 the user then advances the distal end 907 of the reduction tower 900 over at least a portion of the receiver assembly 12 and generally aligns the grasping features 904 of the reduction tower 900 with the tool engaging features i e grip bores 21 of the receiver 20 the clinician then locks the reduction tower 900 by compressing the grasping element 910 towards the housing 901 for example by pressing on the grasping arm 922 until the latch 921 engages the latch keeper 930 when the latch 921 is fully engaged with the latch keeper 930 the grasping features 904 can fully engage the tool engaging features of the receiver 20 as illustrated in fig5 and 59 thus securing the receiver 20 within the distal end 907 of the reduction tower 900 once the reduction tower 900 is securely mated to the receiver assembly 12 of a spinal anchor 10 the interior shaft 902 can be advanced in the direction of the distal end 907 of the reduction tower 900 this can be accomplished in a number of different ways such as for example by attaching a t handle or a torquing tool not shown to the proximal end of the interior shaft 902 and forcing the interior shaft 902 to rotate along its longitudinal axis at least a portion of the interior shaft has exterior.