A card cage formed of mating, identical halves provides parallel slots for circuit boards carrying snap-on retainer clips with integral pawl-like clasps which lock over ridges on the exterior of the card cage. The clip is released from the cage by squeezing the clasps with one hand before withdrawing the circuit board. Slotted side brackets capture mating ribs on the card cage halves to assemble and mount the card cge to a wiring clost panel.
