Text copied from TM9-1985-2 German Explosive Ordnance 1953 :

Description: This igniter is suited for use with trip wires in operating various types of mines and boob traps. The body of the igniter is generally made of brass and consists of the following four parts: The main housing, the guide piece which is screwed to the main housing, the space piece which is screwed to the guide piece and the lower piece which is screwed to the spacer piece. The main housing contains the sliding cylinder and the compression spring. Housed within thesliding cylinder are the striker spring, the striker and the two opposing locking pins which hold the striker in place. The lower piece contains the percussion cap. In the unarmed condition, the safety pin passes through the neck of the sliding cylinder and the holes in the collar. The pin is prevented from falling out by the nut, and by the clip which clamps around the collar.

Operation: After arming, a pull on the trip wire moves the plunger upward against the resistance of the compression spring. The two locking pins are forced outward when they come opposite the open spaces, releasing the striker. The released striker, driven by the striker spring, sets off the percussion cap.

Employment: This igniter is standard for S mines and prepared charges, for booby trapping Tellermines, and for booby traps employing trip wires. Threaded base fits all standard charges, grenades and mines.

Length: 73mm, Diameter: 12mm

Primer shown on the right thanks to Marco.

Photos below M. Jochoms :

Photos below Eric :