terminus 34 is approximately diametrically opposite terminus 32 it is understood that the threads can be extended greater than 360 u00b0 to achieve increased thread engagement also additional thread leads and different linear thread density threads per inch are permitted and may be advantageously chosen in order to permit the threads of the cap to slip past the threads of the neck as shown in fig7 the upper flank 36 of thread 29 slants downwardly outwardly at approximately 45 u00b0 while the lower flank 37 slants downwardly inwardly at an angle of about 10 u00b0 preferably the thread apex 38 is made with as large a radius as possible a portion 41 of vertical stretch 28 is located below the threads 29 extending down to upper shoulder 42 which is horizontal as stated previously instead of threads on the inside of the skirt and outside of the neck one thread may be replaced by a groove further instead of threads 29 being continuous they may be interrupted below shoulder 42 is locking area wall 46 which slants downward outward at an angle of about 10 u00b0 wall 46 terminates in lower shoulder 47 which is also approximately horizontal outwardly of and below shoulder 47 is a lower vertical stretch 48 which at its lower end merges with the container bumper ring segments 49 here shown as four in number may be formed in the stretch 48 to facilitate gripping the container during filling and loading and.