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.
“Vine House Farm niger seed is of very high quality and lacks most of the debris you get in other brands. The goldfinches, redpolls and siskins love it!”
“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”