Take the trunk mat out so that it's easier for u to screw to the box. You want to use at least 2-3 screws depending on the size of the box. Get a respectively sized 1/4 - 1/2" wood board so that it adds a more secured hold. So basically it's going to be wood board on the bottom, trunk mat in the middle, then the enclosure. Use a good 1 3/4" wood screws. Put everything back in the trunk and have fun!