therein the underside of cover 24 has an annular raceway 41 molded therein which opens downwardly in vertically opposing relation to raceway 35 in topwise engagement with the bearings 40 bearings 40 are preferably formed of glass or other dielectric material and are disposed between the raceways 35 and 41 the diameter of bearings 40 is sufficient to support cover 24 above the turntable base 21 in a slightly elevated position with respect to base 21 so that the flange 25 is spaced slightly above flange 22 yet connected loosely thereto by clips 26 the numeral 38 denotes an annular roller case plate of dielectric material which has a series of apertures 39 spaced therearound for loosely receiving the ball bearings 40 and retaining them in spaced relation it has been found however that in practice of the invention the retainer 38 may be provided with a near continuous groove in a still further alternative the plate 38 may be eliminated entirely with a loosely spaced but continuous series of bearings 40 supporting the cover 24 a stub shaft 42 is integrally formed with and on the underside of cover 24 at the center thereof the lower portion of shaft 42 may be for reasons of durability formed or lined with metal material which must be spaced at least.