So I recently came back from a small holiday and flew on Westjet both the 737-600 and the newer 737-800. Anyway, as we were coming in the terminal gate we passed another Westjet 737 parked at the next gate. Of course what caught my eyes were these massive sharklets on the wing tip. In fact I only recently found out they were called sharklets as I always referred to them as winglets.
So I came here and did a search and ran across an old 2014 thread about these sharklets for the 737 and did not want to restart an old thread. In the thread they were available at Authentic Airliners.