Niger seed (nyjer seed or thistle seed) is known to be a favourite of finches, due to the shape and structure their beaks, which are suitable for a smaller type of bird seed.
“My birds love your niger seed.
Sadly one of the bags of niger, I ordered two ,was broken thankfully it was in the larger
bag of finch food .Made a bit of a mess”
“Great product. at a good price. Over time this has attracted a lot of birds - goldfinches ( of course) but also siskins, greenfinches , chaffinches . In fact other finches too as well as woodpigeon when the other feeders are dry. There is a lot of leakage onto the ground which can’t be avoided really and does allow more birds to feed at one time.”