Our Color coded o-ring kits make maintaining your marker easier then ever! After the initial installation if an o-ring happens to break or wear down, you only need to open your boxed o-ring kit, and pull out the similar o-ring of matching color, and swap it out. No more measuring, no more comparing stretched used o-rings with pristine new o-rings, no more sizing charts or sizing cones, no more headaches. Spend less time in the staging area fixing your marker, and more time on the field mowing down the opposition!