Cook's Illustrated mention
From Cook's Illustrated- We tested the JBK Terra Cotta Bread Warmer ($7.95), distributed by Harold Imports Co., a 5- by 3-inch terra cotta tile, about the same size and shape as a smartphone. After you heat it 10 minutes in a 350-degree oven (we also tried soaking it in water and heating it on high in the microwave 3 minutes), you place the hot tile inside a cloth napkin or tea towel in your bread basket, with your warm bread or rolls. The heated tile retains and radiates enough heat to keep the bread warm much longer than cloth-wrapped bread without the tile. We compared its performance to our previous winner, which was discontinued. At 6.5 ounces, it's a little lighter, so it retains slightly less heat, but still performed well.