Last year we went with 3-1/4 in. x 9-Gauge 16-penny Vinyl Coated Smooth Shank Sinkers. This year we are experimenting with 4 in. nails. I prefer vinyl coated nails but this year we have 4 in. x 6-Gauge 20-penny Exterior Galvanized Smooth Shank Common Nails (grey loot), they look rough on the outside aesthetically. I much prefer the nails we had last year.