Straight from the R&D department at RB, a Magnesium head, designed for any RB .21 Offroad engine.

“Lowering the center of gravity is a main concern for any driver. This is why the R&D department of RB designed a new lightened head. Using the magnesium was a first step, but the heat conductivity of the magnesium is pretty different compared to the aluminium. This is why Rody designed a brand new head to have more fins around the hot spot of the plug. After some testing, our team drivers proved that the cooling of the engine is similar to the original head and that the car is much faster due to the lower CG. This Light head fits any RB engine which comes with a separate combustion chamber: it receives a dark grey coating and the new L2G logotype. This head will be produced in a limited quantity as an optional part . You can start ordering it as of now (Partnumber 01076-M). The first production batch should be available by mid-May. We’ll try to get it on time for the EC Warm Up in Auxerre.”