Yes, 4.8mm Monel, dipped in duralac. The doubler itself is coated with arbomast on the rear side to prevent crevice corrosion. I decided the rivet spacing after searching online. There was quite a range between max and min so I went for somewhere near the middle. I suppose I could easily have used a couple more but the pack size limited me to 10 (they aren't cheap) and I wanted a spare or two.
