1x adjuster knob required for 1x seat, 2x adjuster knogbs required for 2x seats for 1x car. Modern replacement knob, shorter than the original, leaving a small amount of thread showing on the slide lever, you could shorten the lever to suit. Original knobs had either a knurled ring near the top or were plain. This knob has a groove near the top.Not for the first time, Alfa Romeo &/or Bertone seem to have designed a non standard dimensioned item when there were many broadly similar items readily available.
 
Part Name: Sprint, SS, Seat Slide Adjuster Knob
AlfaStop Product Code: 1CWF172
Original Alfa Romeo Part No: 1493.68.013
Model: Guilia 101 Series, Giulietta 750 & 101
Quantity Per Car: 2