Rocker guards are one of the first modifications we recommend for anyone planning to take their Jeep off-road. They are inexpensive protection for an easily damaged and expensive area to repair. We typically look for rocker guards that mount either directly to the frame or solidly to body mounts and the body itself. We wanted maximum clearance nd protection for our project JK, so we opted for Poly Performance high-clearance rockers. They mount rigidly to the body and body mounts and provide a smooth, snag-free, tapered surface for obstacles to easily slide under. You gain the advantages of an expensive custom boatside conversion in a simple, affordable, bolt-on package. Here's how they work.
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The optional factory rockers look cool and follow the lines of the Jeep, but they offer very little real protection to your JK's rocker area. Don't forget to pry the clip nuts from the body. If you leave them in they could rattle and drive you nuts when going down the road. |
The outermost sides of the rocker-area body mounts need to be trimmed for the new rocker guards. Four-door JKs require that the additional center body mounts be trimmed as well. An angle grinder works best. The Poly Performance online instructions cover the required trimming in detail. | 
Here is what your trim job will look like. You basically hack off 3/4 inch below the body-mount surface. |
A buddy is a big help but not necessary in hefting the rockers in place. The supplied body-mount bolts and spacers hold them in place. The rockers can be adjusted for height and fitment before drilling into the body panels for the additional mounting hardware. We opted to locate the rockers about a 1/4 inch below the doorframe. | 
Remove the rockers and drill the starter holes out to 17/32 inch. On both right- and left- side rearmost holes (arrow) you'll need to slightly beat back a third inner wall using a punch and hammer. It may be possible to simply trim the mounting bolts to avoid interference. |
Using the supplied tools (Allen bolt and nut) you can install the nutserts into the holes. Once all the nutserts are in, reinstall the rockers using the supplied hardware. | 
After making sure the rockers are level and fit the body well, you can tighten the body-mount bolts. Use the mounting holes as a guide. Drill starter holes using a 25/64-inch drill bit. The two rearmost and two forwardmost mounting holes need to go through two plies of sheet steel. |