Swordfish 201 Universal Metric O-Ring Assortment, 419 Piece Nitrile rubber construction Including 32 metric popular sizes ranging from 3mm(ID) x 6mm (OD) to 50mm(ID) x 57mm(OD) Use in plumbing, hydraulic, air, gas connections and many industrial applications Organized with a hardened storage case with lid chart, and built-in width gauge Manufacturer: swordfish