The pen described is a safety filler with 18-carat gold nib; the second stamping on the turning knob (e.g. M) gives the nib width. Filling takes place with the nib pointing upwards, half turned out; after dropping in the ink, the nib is fully extended for writing and retracted again before closing, in each case with the pen held upwards in order to prevent leakage. Before first filling, the seals are to be checked; a repair service is mostly necessary; alternatively a water test can be made. The model number 25 is engraved both on the nib and on the turning knob and gives the size class within the series (e.g. a 35 existed); the meaning of the S in the mountain symbol on the cap is unclear, possibly a dealer code like Stöffhaas. A shortened cap considerably reduces the material value; the sentimental value as a family piece, however, remains unaffected.