Ammco Self Aligning Nut from GWR. Fits all Ammco Drum Lathes with boring bar dual clamp setup and or all Rotor Lathes with a 6900 or 6950 twin cutter assembly. These high-quality, high tensile strength studs and nuts are engineered to properly secure the Boring Bar Clamp and Twin Cutter Head on Ammco Lathes.