Vitap Sigma 2TA Drill Lead Worm Screw P/N 31402996 OL=765 M12 P=3 D=12.
There is an attaching thread at one end 10mm long, its M8 and 1mm fine pitch. The other end is 27mm long of smooth 8mm diameter shaft.
There are two in the picture, one is sold, so you are buying one piece