Our medium grade orchid bark is only available from us in the UK and is used in our quality hand prepared potting mixes.
Medium grade bark, Sphagnum moss, Rockwool cubes and Clay pebbles can all be used on their own as a potting media, many use Sphagnum moss for Masdevallia and Pleuro's or other fine rooted orchids. Rockwool cubes are popular for Phragmipediums.
Bark can be used for many orchids.
Clay pebbles can be used for semi-hydroponic culture(sitting in water), as a normal media or for humidity/drip trays.