Yes, HEPA filters have a front and back. Make sure to follow the instructions on the HEPA filter when inserting or attaching the filter to your air purifier.
What Happens if I Insert the HEPA Filter the Other Way in My Air Purifier?
HEPA filters have a certain direction for airflow, because one side of the HEPA filter is specially treated to improve airflow performance. Inserting the HEPA filter in the wrong direction may lead to slightly lower filtration performance of the HEPA filter.