Adding these rings can avoid water ingress from the surface. It also prevents scratches on the surface of mounting panel.

The regular type o-ring is suitable for installing the LED Bolt and Indicator Light by nuts:
6mm LED Bolt uses 6mm o-ring
11mm LED Bolt uses 11mm o-ring
16mm LED Bolt uses 16mm o-ring
8mm Indicator Light uses 8mm o-ring

Except the regular type o-ring, now we are offering the flat type o-ring and it's ideal for snap-fit installation by spring:
8mm Premium Side View LED Bolt uses 8mm (Flat Type) o-ring
11mm Premium Side View LED Bolt uses 11mm (Flat Type) o-ring

Available three sizes for our 6mm, 11mm and 16mm LED bolt.