TFM Coupler and TFM Isolator Bundle This is the UltiMaker 2+ TFM Teflon coupler. Replace this part when your original TFM coupler shows signs of wear and friction in the tube. What's Included 1 xTFM Coupler 1 xTFM Coupler Spacer / Isolator (Replaces the older PTFE Coupler and spring) TFM Coupler: In our testing, this part may last 10 times as long as the original PTFE Coupler Installation Instructions here. TFM Coupler Spacer / Isolator: Isolator Spacer 9.4mm that fits on top of the TFM Isolator Coupler. For UM2 / UM2+ Family. Should upgrade if you are using the older PTFE coupler spring. Replaces the older PTFE Coupler spring in the UM2 family. This is a perfectly fitted spacer which no longer applies pressure on the PTFE or TFM coupler so that the coupler lasts a longer amount of print hours before needing replacement.