LEESON NEMA 1 PWM Control: M1740008.00 - Manual (Page 5)

3
Mount the drives vertically or horizontally using the two mounting
keyholes on the back of the case (see Figure 2 on page 4). The
keyholes are 2.5 inches apart. For access to the keyholes from the
inside of the case, remove the six case cover screws, lift the case
cover straight out, and remove the fishpaper from inside the back
cover. Leave the case cover removed to wire the AC line and motor
to the drive.
NOTE: After mounting, return the fishpaper to the inside back
cover, as it provides necessary electrical isolation.
Mounting