Bluing squares are a laundry product that came out of the 19th century when ultramarine blue was synthesized to replace the toxic copper sulfate as a laundry whitener. Blue anil pigment, when crushed in water, produced a bright blue, which, when diluted, would whiten yellow clothes from wear and bleaching. Spiritually, it would be used in similar ways to Waji indigo in Yorubaland- in spiritual baths, for spiritual protection, and later, adopted into the spiritism of the Caribbean. 
In the American South, Rickets Crown Blue and Triple Crown Blue were popular bluing brands because of it's commonality, and because they depicted a crown, perhaps hinting at their use in success magic. Triple Crown brand Bluing squares were very important not because of the formula, but because of its use of imagery- much like Red Devil Lye, or Black Cat Fireworks.
These Triple Crown Bluing Squares come in a pack of three and can be used in spiritual washes for Uncrossing Spells & Workings, spiritsim, for protection, and for Law Keep Away spells.