The feathers range in length from about 9 to 14 inches each. We've arranged them so that if you get one on the shorter side, it'll be paired with one on the longer side to average them out.
For you tenkara anglers out there, this is our favorite color to tie stiff hackle (futsu) kebari with. For the simple stiff hackle flies that we like to tie (usually 3 wraps of the hackle around the shank), we use about 0.75 inches of feather. So based on that math, we would expect to get at least around 25 flies worth of hackle out of this small pack of feathers (though your mileage will certainly vary). This is the hackle we use to tie the Idaho Killer Kebari and the Black and Gold Kebari.
(Note that the second photo is of a fly tied with this hackle; the fly does not come with the purchase of this hackle.)