There are two types of EOT: one type with a "knife clip" (right), another without the "knife clip"(left).

1. You need an allen driver:

2. Unscrew the screw and insert the “knife clip”. For the EOT without the “knife clip”, just skip this step: 

3. Put the knife into the knife clip or the gap in the EOT, the blade toward to the screw:

4. Fasten the screw:

5. Install the EOT lid:

6. Put the EOT into the working head. Note: the there is a red point at the lock part in the EOT and the working head. The red points should be matched to each other. 

7. Fasten the ring: 

8. Connect the EOT cable to the port on the working head: