Align the /dev/mount to rail.
Push the /dev/mount through the holes from behind making sure that the small tab aligns with the middle hole.
Pull the /dev/mount towards your body placing pressure on the rear. It will then snap open and allows to be removed.
The /dev/mount fits square punched hole racks with EIA-310 specifications. Maximum rating per RU 15kg. Do not use if product deformed. *Maximum torque of 3Nm – more can deform your 19“ rail / equipment.