SeeMeCNC's Hi-Temp Jet Kit is used to upgrade your HE280 HotEnd for the Rostock MAX v3, and allow you to print with high temperature materials such as Nylon and Polycarbonate. This Jet Kit should not be used when printing with PLA.
Not for use with PLA.
The SeeMeCNC Jet Kit for their HE280 hotend is only intended for use with higher temp materials such as Nylon and Polycarbonate. High temp materials such as these do not need the PTFE liner to reach nearly as far into the heat break as PLA and ABS do, and SeeMeCNC designed this jet to move the liner up and away from the heat break while increasing the melt zone.
To install, you will need to remove the top mounting PTC adapter of the HE280 and thread this jet in place then reassemble the PTC adapter. The detailed picture shows in red the jet installed in the hotend.