My bowden tube came loose one too many times so I finally bought some push fit connectors from Grainger. I used a 4mm od 1/8 thread. The hotend connector is threaded and was a nice fit. Push fit connector part# KQ2H04-01AS Grainger url: http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=36w998&op=search&Ntt=36w998&N=0&GlobalSearch=true&sst=subset Printed in ABS at 35% infill and two extra shells. I also printed slowly at 35mm/s to get a good print. The push fit connector came with teflon tape on it and was a good fit as designed.