Tamiya TRF Damper X-Rings have X-shaped cross-sections and offer increased oil sealing effect compared to standard O-rings with circular cross-sections. These 50 durometer o-rings are made from special silicone material to help them maintain their shape and sealing ability for a longer period of time, and are recommended for use with silicone based damper oil. This makes them ideal for use with Aeration Dampers such as TAM42198 Buggy HL Aeration Damper Set and TAM54028 Buggy Aeration Oil Filled Damper Set.