Hi Piero,
the adjuster don't fit because they have a 1/4 inch size thread. P11s have a 5/16-26 BSC thread.
Overall lenght is 44,5 mm. The cylindrical part is 7,9 mm dia and 4 mm long. The hexagon part is 6,5 mm long and 11,2 mm across flats. That seems to be a 1/4 inch BSF hex which is 0,445 inch across flats. The nuts are 5/16 BSC with small hex.
Hope this helps.
Peter