Flannel outer and fleece inner. Sewn in channels so the rice and lavender flowers don’t shift all to one end. Fits most sizes. Snapped together with plastic KAM snaps so you can use as slippers or unsnap to use as long pads for aching muscles, stomach aches or just a quick warm up. 1 1/2 – 2 minutes in the microwave. Open 18″x7″, folded and snapped 11″ bottom, 6″ top. Sizes approximate; seams,filling and snaps placement may change size by up to 1/2 inch.** btw these are not walking around slippers, more like sit back, put your feet up and enjoy.