The SRX8 has the steel chassis skidplate as standard feature in the hard anodised chassisplate. As optional items Serpent now releases 2 lighter version of the skidplate
1 x coated alumnium
1 x carbon fibre
Both include the seal/gasket to close the diffcase.
These are the part numbers and weight of them:
600738 Skid plate steel SRX8 (22Gr)
600897 Skid plate alu SRX8 (10Gr)
600898 Skid plate carbon SRX8 (8Gr)