An explosion-proof enclosure includes a front cover (first housing half or portion) and a rear cover (second housing half or portion) joined together by a retention member inserted into a passageway at least partially formed by structures of both the front cover and the rear cover. The enclosure includes an internal chamber for containing an associated electronic device. The passageway generally extends peripherally about the internal chamber. In one exemplary embodiment, the retention member is a ball-chain and the passageway completely surrounds the internal chamber such that respective end portions of the ball-chain overlap. A sealing element is provided for sealing respective mating surfaces of the front cover and rear cover. In another example, the retention member is a rigid split retention member.