The process of facial aging is a result of intricate alterations occurring at both the microscopic and macroscopic levels, leading to changes in facial volume. The observed alterations can be attributed to the process of bone structure resorption, the influence of gravity, redistribution of subcutaneous fat, and injury to the skin. Dermal fillers are utilized for the purpose of enhancing facial features in accordance with the aesthetic ideals of beauty.

KOS® XL in the dermis regulates water balance, osmotic pressure and ion flow and functions as a sieve, excluding certain molecules, enhancing the extracellular domain of cell surfaces and stabilizes skin structures by electrostatic interactions.

The Research Question of the present study is the following: to collect sufficient clinical data to demonstrate compliance with the General Safety and Performance Requirements of KOS® XL when used as intended.

Inclusion Criteria:

• Females and males ≥ 22years of age
• Signed informed consent by the subject
• Subject with grade from 3 to 5 on the FVLS.
• Ability to follow study instructions and likely to complete all required visits
• Reliable methods of contraception which result in a low failure rate (i.e. less than 1 % per year) for women of childbearing potential, e.g. implants, injectables, combined oral contraceptives, some intrauterine -devices, sexual abstinence or vasectomized partner) for the entire study duration.

Exclusion Criteria:

1. Using any new over-the-counter or prescription oral or topical, anti-wrinkle products within 30 days before enrolment or planning to begin using such products during the study (Subjects who have been on a regimen of such products for at least 30 days are eligible for the study if they intend to continue their regimen throughout the study).
2. Subject with a scar, moles or anything on the face which might interfere with the evaluation
3. Subject having received treatment with a laser, a dermabrasion, a surgery, a deep chemical peeling or other ablative procedure on the face within the past 12 months prior to inclusion
4. Subject having received injection with a resorbable filling product in the face area within the past 18 months prior to inclusion
5. Subject having received at any time injection with a slowly resorbable filling product (polylactic acid, calcium hydroxyapatite, combinations of hyaluronic acid (HA) and hypromellose, HA and dextran microbeads or HA and TriCalcium Phosphate (TCP), …) or with a non-resorbable filling product (polyacrylamide, silicone, combination of methacrylic polymers and collagen, polymer particles, …)
6. History of or active autoimmune disease/immune deficiency
7. Suffering from inflammatory and/or infectious cutaneous disorders in or near the studied zones (herpes, acne, mycosis, papilloma…)
8. Prone to hypertrophic scars
9. History of allergy to hyaluronic acid or any of the product's components
10. History of allergy to lidocaine or local anaesthesia of amide compounds
11. Known case of porphyria
12. Pregnancy or lactation
13. Taking medications and/or substances known to increase coagulation time (e.g., aspirin, ibuprofen, or herbal supplements) 10 days prior to treatment
14. Have a condition or be in a situation that, in the physician's opinion, may put the subject at significant risk, may confound the study results, or may interfere significantly with the subject's participation in the study
15. Untreated epilepsy
16. Hypersensitivity to gram positive bacterial proteins as hyaluronic acid is produced by Streptococcus type bacteria.