The plunger of the Stainless Steel-Spring bolts GN 313 does not protrude in the inoperative position.
It can be operated manually or in Type D and DK mechanically (pneumatic cylinder, cam plate, etc.) when it will protrude only as long as it is operated.
Using the internal thread at identification 2 on the pressure side, special pressure bolts or a rod arrangement can be operated, for instance.