Winco GN 313 RoHS-compliant spring bolts come in metric sizes; versions with or without a push/pull knob and with or without an internal thread in the plunger pin are available. The plunger pin is operated manually with the push/pull knob or mechanically via a pneumatic cylinder, cam plate, etc. The plunger pin protrudes only as long as the bolt is in the operation mode.
J.W. Winco; 800-877-8351; www.jwwinco.com