A fine gauge, compound knit fabric with a smooth surface on both front and back, composed of two separate 1 x 1 rib
fabrics interknitted to form one cloth, made on an interlock machine
. The fabric was traditionally used for underwear, but today is being used for apparel. Despite the name of the fabric, poorly made interlock develops runs at the edges and all interlock knits should be reinforced or finished
in some way at these edges.