Sennheiser evolution wireless series EM 100 Instruction Manual page 17

Putting the receiver into operation
16
To mount the receivers into a rack using the GA 3 rack adapter:
Place the two receivers side by side upside-down onto a flat surface.
Secure the jointing plate
screws (M 3x6).
The rack mount "ears" are mounted instead of the stacking elements:
Secure the rack mount "ears" to the receivers in the same way as
described for the stacking elements (see page 11).
To mount the antennas:
Use remote antennas, if necessary in conjunction with the ASA 1
antenna splitter (see "Accessories and spare parts" on page 49).
To mount the receivers into the rack:
Slide the receivers into the 19" rack.
Secure the rack mount "ears" to the 19" rack.
to the receivers using six recessed head