Not sure if this has been posted already but I just found an adapter from Maymom for the Spectra pump to use with Medela pump parts.

Unfortunately the adapter isn't sold individually but I still thought it was worth it because the flanges fit Medela bottles.

I previously had the Medela PISA and had a ton of flanges for Medela parts. I had hacked the Spectra to use with Medela parts but the tubing would fall out.