Fir bark can make an excellent standalone potting medium (for orchids and epiphytes), but it really shines as part of a tropical substrate mix. 
Fir bark is the best type of bark for adding to any grow media because it breaks down very slowly.  Fir bark can help aerate soil, improve drainage and prevent root rot.
It also can be used sprinkled on top of your pot as a nice looking top dressing that helps improve the humidity for your plants!
I love fir bark because when wet it gives off the most lovely aroma too. 
Offered in two sizes.  The main photo shows the smaller size and the additional photos with red background show the larger size