These are a great alternative to the Abu 4490 E-clip. Easier to install and remove without fear of getting lost. Additionally, they put less friction on the cog wheel when used in place of the 4490 E-clip. These o-rings can be used to secure the spool pinion on the 1500C/2500C models and the pinion cup removed, creating less potential for friction. Sold in packs of 5.