I think they stopped making the erg cover once they started making the alpha and phaze...they started making covers with a yearly naming focus like AX-16
Anywho in no particular order the rad4s are as follows
Code Red R2S Hyrbid
Code X R2S Solid
Code Star R2S gen4
Code Black Limited NRG Solid
Code Red Sp R3S Solid
Code Blue R3S Pearl
Code Gold R2X Pearl
Code Green R2X Pearl
Code Black R2S Pearl
Code 30 R2S Pearl
Code Black Sp R2S pearl
Code Blue Sp NRG solid
Code Platinum R2X pearl
Code Black Limited NRG Solid
Code Zero R2S pearl
Code Black Nano Pearl NRG Pearl
Code Red Limited NRG Solid
Code Perfect R2S Hybrid
According to the chart I have from the technical director..
Erg is stronger than R3S
R3S is considerably stronger than R2X and R2S...
I thought my ERG byte was awfully weak...but to each their own.
Good luck!!!
I'd say myself time and money and go after a code red.