For exterior quarter log siding we recommend the use of galvanized siding nails (8 penny ring shank) or corrosion resistant decking screws (2″ – 2.5″ long). For exterior half log siding we recommend the use of corrosion resistant decking screws (2.5″ – 3″ long) or galvanized siding nails (14 penny ring shank). For interior products like Knotty Pine Paneling any finish nails or brads would suffice (16 gauge 1.75″- 2.0″) . Additional info at the following link:  https://www.woodworkersshoppe.com/wp-content/uploads/2015/02/09-Fasteners.pdf