JRP Riveting Products M6 x 15.5 (0.5-2.5) A4 St.Stl Countersunk Head Round Knurled Body Open JRP Rivet Nuts (Box of 500)The JRP Riveting Products M6 x 15. 5 (0. 5 2. 5) A4 St. Stl Countersunk Head Round Knurled Body Open Rivet Nuts are designed for secure fastening in various applications. Made from durable A4 stainless steel, these rivet nuts provide excellent corrosion resistance and strength. High Quality A4 Stainless Steel for Durability Knurled Body for Enhanced Grip and Stability Counter Sunk Head Design for Flush Finish Open Type for Easy Installation Suitable