Single 16mm flip lock screw for folding poles OR 18mm flip lock for 2 section poles with graphics. Flip lock replacements include the hand tighten nut as well. These are the flip locks found on York Nordic brand poles and work whether you have the nordic grip or the trek/hike grip.
NOTE: our go pro camera poles have 3 flip locks all at the following sizes (14mm at bottom, 16mm in middle, and 18mm at top grip secion) so please for Go Pro replacement parts.