End Cap for 75mm semi-flex ducting

This is a end-cap  for use with 75mm sem-flex ducting.  This fits inside the ducting to keep dust out during installation.  It was designed to fit 75mm style of semi-flex ducting by Blauburg (BlauFast) or Zehnder.  

I printed the end cap in Sunlu PETG. I have kept the tolerance as close to the inside diameter of the ducting to reduce the chance of leakage.