The large internal bypass prevents swabbing during the trip in or out of the well and allows high volume circulation. Tubing pressure at the Packer acts to hold the bypass closed to prevent it from opening during injection operations. Additionally, tubing pressure forces the upper slips into the casing to prevent the Packer from being pumped up the hole. The Packer is set by quarter-turn right hand rotation at the tool and slacking off the desired weight to pack off the annulus. Pick up the string to open the bypass and unset the Packer.