that grip is for rtp rails; you need one for classic rails (or, get an rtp / emag / tac-1 rail).
if you decide to sell that grip to get
I think I may have the fore grip you are looking for. I will upload a picture of it tonight or tomorrow but it looks like it fits that rail and is red.
Selling my Crossover. Bought it originally because I liked the idea of it, the closest I could get to owning a modernized EMag. Had Tippmann install