RHA: The RHA collection is Resilient Hyaluronic Acid dermal fillers. These fillers are designed for facial dynamics; it's the latest advancement in HA fillers in more than a decade! Hyaluronic acid is already naturally occurring in the body to help provide moisture, volume, and structure to the skin. As time goes on our bodies produce less HA. RHA will closely mimic that HA to give you a more natural look.