1 set of O-rings for the Gingko chain idler with 11 teeth.
When the o-rings are worn, you do not have to dismount the idler.
Just cut out the old o-rings and pull the new ones over the idler flanks. Done!
You need 4 o-rings for the idlers with 11 and 19 teeth and 2 o-rings per idler for all other sizes.
Dimensions: 34 mm x 2 mm