14" Heated Bird Bath Dish Insert. Fits any 14" Bird bath Ring. This unit is designed for use on our clamp, pole, screw or ground level bath support rings. The unit is not recommended for placement in large bird bath bowls which may fill with water, or on the ground. Possible water seepage will damage the product, and void the one year warranty. Some icing on the surface of the water is normal when temperatures are this low, especially if there is a breeze. Your birdbath is not defective if ice begins to form around the rim.