Lauda IN 550 XT FC Operation Manual page 19

Fig. 3: Ring bolt (example)
V4
Fig. 2: Unpacking instructions
7. Fig. 2: Remove the ring bolts from the packaging.
8. Fig. 4: Screw the two ring bolts all the way into the thread connection
Ç (M10 or M16) on the top of the casing. Turn them clockwise to do
so.
Integral process thermostats with flow control unit 19 / 171