Special plastic spanner for Bluemels column locking nut, these don't damage the locking nut unlike metal grips & a soft rag, can get the nut tighter than strong fingers & thumb.

They are 8mm thick & made from strong non damaging acetal which stops the column hex nut getting damaged.

It is like a reversed pair of scissors, it slips over the column then loops over the nut & as you grip the spanner it clamps / tightens on the nut, 1st photo, these also fit the black Girling brake fluid cap used on DB2 to DB4