Tool-less, limited rotation, telescoping fastener

A field-replaceable unit is reversibly secured in place using two captive fasteners. Each fastener includes a telescoping knob that rotates 180 degrees in a first direction to engage a latch mechanism and rotates 180 degrees in the opposite direction to disengage the latch mechanism. The knob automatically extends when the latch mechanism is disengaged. The knob alternately extends and retracts in response to being successively pressed when the latch mechanism is engaged. The knob has two cutaways formed along outside edges to facilitate a two-finger grip for knob rotation and pulling the unit out of another module. A circular groove centered on an axis of rotation of the knob has a contrasting coloration and provides a visual and tactile indication of know location. A nub indicates rotational position of the knob.