R1 protein WPI by Rule 1 Proteins is made entirely of ultra-pure 100 percent whey isolate and fast-acting whey hydrolysate. Whey concentrates, creamers, gums, amino spiking, and other fillers that dilute what you really came for protein have all been eliminated. The outcome is a Protein Purity Percentage of up to 87 percent, which is the highest in the industry.