This is not a mudguard. However, the holes are only for attaching the screws that hold the protective cover to the side. There is an 8 mil bolt in the center. The holes you drill press the outside edge against the rear bumper which is plastic (DO NOT USE A LARGE DRILL). I recommend inserting the screw half-tight to allow the edge to attach, then drilling one hole at a time to make sure the fit is good (don't over-tighten the outer screws), then fully tightening the screw. The only issue I had was that the wheel can be difficult to penetrate to get to the screw (the bigger the wheel the worse) and in the same area a screw clamp has to be removed to replace it with a new one to replace longer screw . They recommend removing the wheel but in most cases this step doesn't work, but it's tricky, the screws were easy to install as in my case they aren't blocked by the big wheel, that may be different in others .