B6/B6.1/B6.2/T6.1/SC6.1 O-ring Battery Strap which are made from glossy 2.5mm carbon fiber, these hooks are secure and you can make adjustments to your shorty pack. Unlike slotted systems that can slide forward in a crash, these stay secure with a range of different positions including flipping them over to get the full range of adjustment. An o-ring (two provided with your purchase per kit) holds your pack secure enough to keep it in place but also flexible enough to allow for the chassis to flex underneath. The o-ring hooks are centrally located to the battery hooks, so the o-ring is always centrally located to your battery pack. Like any NathoBuilds products these have been tested on multiple cars on different track conditions. If you are looking for that extra edge in your Team Associated B6/B6.1/B6.2/T6.1/SC6.1 these will make your racing experience more enjoyable.