1. In the grading hoop increased in the plastic stopper, flexible stopper to reach the rubber stopper after the pressure down, the rubber stopper wall effect is good, can make the casing wall cleaning, to ensure the smooth fall of the internal attachment.
2. In the upper part of the plastic plug design open the plug seat protective sleeve, only the rubber plug left to open the grading hoop.
3. Close the cover with a limit mechanism, open the circulation hole, the stopper can move to achieve the level hoops closed.
4. Close the cover to reach the closed position, the internal annex to be able to fall off.
5 in the rubber stopper above the special pressure fluid, to ensure that all the internal attachments fall off in place.