Thumper Fabrication TF040702-X Defender Nerf Rails (3-seat)Thumper Fabrication TF040702 X Defender Nerf Rails (3 seat) If you're looking for a nerf rail or side step that's big, bad, and built to last, look no further than the Thumper Fab Defender Nerf Rails for your Can Am Defender. These beefy nerf rails are made from the same tubing that we use for roll cages, so you know they're tough enough to handle whatever you throw at them. Plus, they're compatible with your Can Am Defender Limited doors, so you can