Ammco Self Aligning Nut and Long Stud Kit from GWR. Fits all Ammco Rotor Lathes with a 6900 or 6950 Twin Cutter assembly. and all Ammco Drum Lathes with Boring Bar dual clamp setup. 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.