Originally Posted by KansasCityRellik
" HNBR, aka. Therban: This material is chemically similar to Buna, except the materials are hydrogenized (addition of hydrogen). The resulting material tends to hold up longer than urethane or buna, while maintaining the same durometer as the lower-quality Buna rings. Although significantly more expensive, ideally this is the most long-lasting o-ring type available due to the long tolerances. "
**Quoted from ZDSPB.com**
So its the green ones that come stock on the NXT Shockers. Thats what I thought.