G-Force CNC Weighted Tail Grips for JR Vibe 50 The G-Force weighted CNC tail blade grips are a bolt-on upgrade with performance that you can feel. The weights are used to reduce the momentum of the blades that have a tendency to center themselves. The G-Force tail blade grips incorporate weighted flanges closest to the center near the hub and linkage point for best performance. The flange is also pre-tapped so you can add more weight if necessary to fine tune your setup.