In one implementation, an electronic device comprises a first housing portion including a wall and a detent member on the interior of the wall and a second housing portion to attach to the first housing portion to form an enclosure. A retractable bolt member mounted in the second housing portion can engage the detent member in a first position and can disengage the detent member in a second position. The bolt member can be resiliently biased to the first position and at least part of the bolt member has magnetic properties that force the bolt member to be repelled to the second position if a magnetic field is applied outside the wall adjacent the detent to interact with the bolt member, so that the first housing portion can be detached from the second housing portion.