Designed to be used in conjunction with AIRAID's other UBI system components, the new Universal Cold air box features a built-in velocity stack to promote airflow along with a premium SynthaFlow oiled air filter that is large enough to feed most popular engine combinations. The air box inlet size is 4" in diameter but can be adapted to work with UBI tubes from 3" to 5" in diameter. Please note, the UBI Universal Air Box is intended for use with other AIRAID UBI components that are sold separately.