Artist Reply: Thank you so much ! They are sealed with an acrylic concrete sealer ( the same as is used on a patio!), and are primarily meant to be outdoor garden art, but many people who aquire my pieces use them indoors. The backs are rough, I would place them on a soft pad or cover the back with felt. The hangers are made from aluminum wire, so can be bent flat if needed, but usually they sit pretty nicely anyway. I don't recommend that they stay outside in snowy winter weather, cold wouldn't hurt them, but cold and ice could. Thanks again!