Hand-made Red Oak Boxes. This are oiled to bring out the grain. 
There are three different sizes and come with the jars, they are glued in. 
 
Small 6.625"H x 5.5"W x 6"L
Medium 7.875"H x 7.325"W x 8.5"L
Large 10.5"H x 7.325"W x 10.625"L