HOUSE OF PLLA® HOP+, has the highest grade of poly-l-lactic acid (PLLA) on the market. It is a bio-compatible ingredient used in dissolvable stitches, soft tissue implants, and other types of implants. PLLA is a collagen bio stimulater. PLLA boosts collagen production resulting in filler-like results without the costly filler treatments. With continued use, the skin continues to improve.