as cone 26 moves down the lower slips 28 ride upwardly on the cone and move outwardly until they grip into the wall of casing 29 the lower slips are then in the fully set position shown in fig2 b the next step is to set the upper slips 18 as illustrated in fig3 a and 3b this sequence is started by applying enough additional downward force through the setting tool to shear off the larger shear screws 17 which secure the sleeve 14 to the upper cone 16 when these screws are sheared the sleeve 14 moves downwardly on the upper cone at the same time the sub piece pushes the upper slips 18 downwardly on the upper cone this causes the upper slips to move outwardly until they grip into the wall of casing 29 the upper slips are then in the fully set position shown in fig3 b the next step is to release the setting tool from the packer tool this is done by applying enough additional downward force against the setting tool to shear the connection which fastens the setting tool to the top of mandrel 10 this connection is not shown in the drawings when the connection is broken the tubing string and setting tool are then pulled out of the casing so that the packer tool is left in the casing as a permanent.