chamber 316 piston 302 is urged in an upward direction with respect to cylinder 304 pins 312 are manufactured and mounted in an engineered configuration to shear at a predetermined pressure present in variable volume chamber 316 allowing piston 302 to reciprocate with respect to cylinder 304 to actuate and set packer assembly 200 in fig5 d seal housings 402 and 404 are shown connected together by mating threads 410 to prevent inadvertent separation a plurality of radially extending set screws or pins 412 lock the threads 410 in an assembled position a plurality of annular seals 414 seal the joint between seal housings 402 and 404 lower end 416 of lower cylindrical seal housing 404 is open and has a frustoconical guide surface at shoulder 418 formed therein the interior of end 416 forms an axially ending cylindrical sealing surface 420 latch element 422 is located in the interior of female latch assembly 400 at the juncture of the upper and lower cylindrical seal housings 402 and 404 details of the structure of the latch element 422 and its mounting within the female latch assembly 400 will be described by reference to the fig6 and 8 in fig6 the juncture between the upper and lower cylindrical seal housings 402 and 404 is shown the latch element 422 removed for clarity the cylindrical inner wall 424 has a diameter which approximates the cylindrical sealing surface 420 in housing 404 extending axially from and concentrically with cylindrical inner wall 424 is an enlarged diameter cylindrical recess 426 a second larger cylindrical recess 428.