The Sur-Latch Shear Release Seal Unit Assembly is used with Petrostar Seal Bore Packers. The seal unit provides a tubing-to-packer seal, a positive locking condition, for tubing left hand rotational release or straight pull shear release. The seal unit assembly is made up to the lower most part of the tubing string at the surface if a wireline-set packer is used. If a hydraulic packer is used, the seal unit assembly may be installed into the packer at the surface and RIH. The seal unit packing contacts the mating hone bore in the packer to form a seal.  The floating latch moves up enough to allow its collet-type ends to flex inward. This allows the mating left-hand threads engaged in the packer. To release, a straight pull above the predetermined force will shear the shear pins, allow the latch to move downward and collapsed inward, disengaged from the packer head. Alternatively, by right hand rotational method with a tensile force 1,000 to 1,500 lb force.