Insulator - for Ultimaker2 - goes between white teflon isolator and heater block (Olsson or Ultimaker).
This precision machined upgrade insulates the Teflon coupler from the hot end top end, enabling the Teflon coupler to live for a long time. (image is from engineering sample). The Teflon will still deform, but much more slowly.
It`s underside is no longer in contact with the Teflon, but on retractions, the hot plastic still touches the inside wall.
Over time the Teflon still forfeits sufficiently of it`s properties to start imploding and “squeezing” the filament and hot retracted plastic.
This part is in shape of a “wafer chip” and installs easily together with “The Olsson Block”. It is a perfect fit, so your SS coupler (the steel item with the radial holes in it) needs to be totally clean inside.
The I2K will save your Teflon coupler from deforming for a long time, and save you from print head assembly rebuilds. We have 500+ hours at 260C varied printing, and no deforming. A lot of retractions @260+ influences longevity of the Teflon negatively. The chip itself can take 295C continuously, and will outlast your printer if you print at maximum this temperature.