Diffuser Glass Bottle (Square) 200 ml With its simple and elegant design, this bottle fits into any home decor. The wooden caps have a protective metal ring to prevent staining from the oils. These wooden caps come in a natural state ready for staining or painting. We also highly recommend that they be treated with a wood sealer to prevent cracking and protect them from any drops of oil that could discolor them. Included is a plastic plug which allows for easy transporting of oil in the bottle.