What do K, R, and U mean on food and other packages? Cecil replies: The circled R, as I think most people know, stands for registered trademark. The K, circled K, and the circled U are all meant to indicate the product is kosher. Therefore, Frank, what you have in your closet there is a box of kosher storage bags. This may strike you as taking this kosher business a bit far, but allow me to explain.