SAGER TRANSPARO BARREL OF INK GREEN MARBLE PENCIL ADAPTER FOR FOUNTAIN PEN. VERY RARE ACCESSORY FOR THE SAGER PENS. IT WILL REPLACE THE BLINDCAP ON CERTAIN SAGER PENS THAT HAVE BLINDCAPS AND NOT FIXED BOTTOM KNOBS. ALSO PLEASE CHECK YOUR BARREL DIAMETER AT THE BOTTOM FOR FIT FOR YOUR PEN. ALL THREADS WERE THE SAME. DIAMETER OF THIS ADAPTER IS 1/2 INCH. **PLEASE NOTE: THE ADAPTER IS PHOTOGRAPHED WITH A STUB SAGER PEN FOR DEMONSTRATION PURPOSES ONLY - THE PEN IS NOT INCLUDED WITH THIS ADAPTER - PEN IS LISTED SEPARATELY.