I've had a metal log holder for ten years or more. The squirrels/chipmunks chewed and removed the plastic stoppers. Found and tried these substitutes. They fit perfectly! And now I have a backup in case the creatures gnaw through the new ones.
Pros
SBD (pack of 10) 2 x 1" (14-20 Ga) Rectangular Tube Plastic Plug End Plug Insert (Fits ID L 1.83-1.93", W 0.84-0.93") 1 x 2" Fence Post decorative inserts .