An apparatus for redundant retention of a device comprises a mountable device comprising a first side having a first fastening portion and a second fastening portion, at the first fastening portion, an elongated body having an inclined face parallel to and protruding from the first side and a flat face perpendicular to the first side, at the second fastening portion, a circular body with a smooth circular face, the circular body protruding from the first side, a removable device comprising a corresponding first side having a corresponding first fastening portion and a corresponding second fastening portion, at the corresponding first fastening portion, a first groove for receiving the elongated body and engaging a first retention mechanism, at the corresponding second fastening portion, a second groove for receiving the circular body and engaging a second retention mechanism.