Magnepan MG 20.1 - Manual (Page 4)

B) Locate the four holes in the fabric along back side of the panel.
C) Note that one section of the support feet is slightly longer than the
other. Place the longer section toward the front of the speaker.
D) Align the holes in the foot with the holes in the panel. Using your
fingers, insert the bolts through the foot and into the panel until
they engage nuts in the panel. Care should be taken so the bolts
do not cross-thread. Final tightening is done with a No. 2 Phillips
screwdriver.
E) Repeat Steps C & D for the remaining feet.
There are threaded holes on the bottom of each speaker support which
may be used to install spikes for installation on deep carpeting if desired.