Tamiya TRF blank damper pistons
Tamiya have introduced two new versions of optional blank pistons. One version of piston features 6 dimples allowing you to freely select the number and diameter of the holes and they work with a wide range of shocks. The second, are TRF Aeration damper pistons which features 8 dimples again allowing you to select the number and diameter of the holes and can be used with the buggy aeration oil filled damper set.
Source: Tamiya [tamiya.com]