Strung Chinese is a go-to feather in the steelhead fly tying world. It can be used as a collar, when you aren't looking to add too much bulk to a station, just contrast or color. It is also often used wrapped through the body on intruder flies to fill them out a bit. These packs come with a great amount of feathers, with consistent sizes and very vibrant colors.
These feathers are also popular in the trout world. There they are mainly palmered the bodies of streamer patterns. A less common, but still productive use for these feathers is a tail feathers in a wide array of flies from trout, bass to saltwater.