Hook backing is sewn on, this is not glued like some other patches. When patch gets dirty - simply apply some liquid soap and some warm water and scrub off the debris. product is very well designed.Construction is very durable and will not wear down easily.Looks really cool, nice and thick, don't have to worry about it being damaged on the outside of my backpack. Quite Good for Your Bag,Cap,Jacket or Accessories. This Quality PVC Patch is Really Great for military Kit and Apparel and Jacket,Cap,Backpack,etc.Hook backing to secure onto loop patch on uniforms, helmets,outwear or fleece jacket sleeves, tactical vests,bags, backpacks, etc The origins of morale patches trace back to the fighter plane nose art of World War I. During the Vietnam War, units often created ironic, humorous morale patches.