fins (of a fountain pen feed); comb feed
Technical term in fountain pen design; refers to the comb-like grooves on the feed that regulate ink flow.
When the fins of a fountain pen feed get clogged, ink flow becomes poor.
This nib has many fins on the feed, so ink is supplied steadily.
Compound of 櫛 (くし, 'comb') and 溝 (みぞ, 'groove'), describing the comb-like grooves on a fountain pen feed.