I've installed them in as little as 1/4" balsa without any issues. 3/8" on 40% IMAC airplanes. I do cut some of the excess length off. The important thing is the prep. Clean them with alcohol, sand all the gloss off with 220 grit, clean again with alcohol. They need to fit tight in the holes. Use either epoxy or Gorilla glue. If using GG, it takes very little.