Packer is a full-opening, V-RTTS packer used for testing, treating, and squeeze cementing  operations. In most cases, the tool runs with a circulating valve assembly. Packer body  includes a J-slot mechanism , mechanical slips , packer elements,  and hydraulic slips. Large, heavy-duty slips in the hydraulic hold down mechanism help  prevent the tool from being pumped up the hole. Automatic J-slot sleeves are standard equipment on all packer bodies. Circulating valve, if used, is a locked-open/locked-closed type that serves as both a  circulating valve and bypass. Valve automatically locks in the closed position when the  packer sets. During testing or squeezing operations, the lock prevents the valve from being  pumped open. A straight J-slot in the locked-open position matches with a straight J-slot  (optional) in the packer body. This combination eliminates the need to turn the tubing to  close the circulating valve or reset the packer after the tubing has been displaced with  cement.