Chanter reeds are double reeds. That means they have two blades of bamboo that vibrate together to produce sound. It is vital that those two blades be symmetrical. If one blade is thicker or larger than the other the reed will not produce a good sound.
Blade symmetry should be checked when the reeds first arrive. Look for symmetry in the blade length and its thickness. If the blades do not match some sanding/scraping will improve the sound. When adjusting the reed, care must be taken to shave/sand evenly on both blades making them balance properly.
