This is an optional hard anodized aluminum CNC front lower arm holders for OFNA buggies, and fits the Jammin X1 RTR and X1 CR buggies. This is an optional part and provides the holes in the same positions as the 'A' lower block. You must use this part along with the upper 'A' block, either the plastic or aluminum version!
The 'A' blocks make the rear of the front arms sit lower than the 'B' blocks, which increases the front kickup and also increases the amount of front caster at the steering hubs. This will provide less corner entry steering but more corner exit or on power steering. If you need more steering exiting corners on power, or need more steering in long sweepers when you are on the power, try using the 'A' blocks.