the incrementing sleeve 180 which rotates in return due to the cam profile 182 see fig4 once the sleeve 140 reaches this fully closed position the indexing sleeve 180 has fully rotated so that it is ready to increment to open setting number one when pressure is once again applied to the open control line 64 the structure of the closing mechanism may be varied in other embodiments of the invention referring back to fig4 the cam groove 162 of the increment sleeve 160 has a profile that permits the increment sleeve 160 to rotate after each engagement with the indexing sleeve 180 and then return to its initial position ready to increment to open setting number one after engagement with the sleeve 140 fig5 6 7 8 and 9 illustrate the interaction between the increment 160 and indexing 180 sleeves and the role of the cam groove 162 in accordance with some embodiments of the invention fig5 depicts the state of the incrementing sleeve 160 and indexing sleeve 180 sleeves when pressure is applied to the open control line 64 the close control line 62 is assumed to be de pressurized this pressure produces an axial force 200 via the floating piston 150 that pushes the incrementing sleeve 160 towards the indexing sleeve 180 until the indexing sleeve 180 is engaged by the lower finger 168 of the incrementing sleeve 160 referring to fig6 the finger 168 comes into contact with one of the stepped faces of the.