The 18mm Engine Retainers were designed to be used with the Aerotech 18mm reloadable rocket engines, not the standard single-use motors (from Estes, Quest, Apogee, or Aerotech). But there is some good news! With a little bit of tape, you can use the retainers with 18mm single-use motors too. This video will show you how to add the tape in the right spot so that you can use single-use motors with the 18mm engine retainers.