Abstract: An improved moisture and dust seal assembly is disclosed which is especially suited for application in small hand-held radio apparatus or the like which includes a molded plastic enclosure. A vertical wall is provided on one of the mating members forming the enclosure, such as the cover. The wall has essentially right angle corners and is adapted to receive a standard O-ring thereabout. The assembly is completed by affixing a ribbon-like member, in the form of a closed loop, to the top of the verticle wall. The ribbon-like member extends a predetermined distance beyond the edge of the verticle wall to form a groove-like space for retaining the O-ring. The ribbon-like member may be affixed to the top of the wall by a convenient heat staking operation.