Fichtel & Sachs (F&S) 18 Tooth Bicycle Sprocket.
For hub geared bikes.
For 3/32" (7 speed derailleur type) chain.
Nice Quality & also fits Sturmey-Archer Hubs.
Great if you want to use a 3/32" alloy chainwheel and a slinky narrow chain to get a lightweight transmission.
Gives a good range of gears with a 3 speed hub on a 26" diameter wheel.
Thanks for looking!