Leather neck protection riveted to a thin clock spring is pressed to the neck by an eccentric lever. Adjustment screw for different neck sizes. A slot in the end of the bar prevents it from turning. Was marketed by GEWA, Germany. Guide posts at each end of the bar.
Plastic tubing protects the neck.
More information wanted. Bringe Eccentric lever capo. The eccentric edge is bluntly tothed to prevent slipping. US patent 1979 by John E Bringe. I guess Shubb was inspired by the capo above.