This is a direct bolt in replacement of the IS300 or 2nd Gen GS and LS side markers. No modifications needed to anything. 
 
Black Housing: Less Light emission, Pattern More Visible
White Housing: More Light emission, Pattern Less Visible
White Glow: Same as White but Glows in the Dark!
 
Price includes both sides. Hardware Included. You will need to reuse your original washers that hold the sidemarkers onto the bumper from behind.