Using your RokBlokz mud flaps is easy. First, find the existing OEM mounting locations on your 2015 - 2021 Subaru WRX or WRX STI. You don't need to drill any holes. Just follow the instructions included with the kit to fit the mud flaps using the provided stainless - steel and rust - resistant mounting hardware. For 2018+ Premium models, you might need to make a couple of small changes to the installation process. Note that these mud flaps may not work with FACTORY STI REAR QUARTER UNDERSPOILERS or AERO SPLASH GUARDS. To maintain your mud flaps, simply wash them with mild soap and water regularly. They are designed to be durable in extreme heat and cold, so you don't have to worry too much about the weather conditions. With these mud flaps, you can enjoy great protection for your car's lower rocker panels, lower door areas, and rear bumper corners from road debris and gravel.