R.S.P 4wt Suspension Fluid isn't a new product, but now it's got a new home inside all of Fox's GRIP style dampers.

For use in selected Fox shocks, fork dampers and fork lower legs. 

This is a replacement for the Fox 5wt Teflon oil. Fox has started using this for their 2025 range and has back-dated it as compatible with all GRIP/GRIP2/FIT4 dampers.