Reference: 
1) Reilly DM,  Lozano J. Skin collagen through the lifestages: importance for skin health and beauty. Plast Aesthet Res 2021;8:2. http://dx.doi.org/10.20517/2347-9264.2020.153
2) Farage MA, Miller KW, Elsner P, Maibach HI. Characteristics of the Aging Skin. Adv Wound Care (New Rochelle). 2013 Feb;2(1):5-10. doi: 10.1089/wound.2011.0356. PMID: 24527317; PMCID: PMC3840548.

Published clinical studies by sponsor BTL Industries JSC (more provided on request)
1) Chilukuri S, Denjean D, Fouque L. Treating multiple body parts for skin laxity and fat deposits using a novel focused radiofrequency device with an ultrasound component: Safety and efficacy study. Journal of Cosmetic Dermatology. 2017;16(4):476-479. doi:10.1111/jocd.12448
2) McDaniel D, Weiss R, Weiss M, Mazur C, Griffen C. Two-treatment protocol for skin laxity using 90-Watt dynamic monopolar radiofrequency device with real-time impedance intelligence monitoring. J Drugs Dermatol. 2014;13(9):1112-1117.
3) McDaniel D, Fritz K, Machovcova A, Bernardy J. A Focused Monopolar Radiofrequency Causes Apoptosis: A Porcine Model. Journal of drugs in dermatology : JDD. 2014;13:1336-1340.
4) Chilukuri S, Lupton J. “Deep Heating” Noninvasive Skin Tightening Devices: Review of Effectiveness and Patient Satisfaction. J Drugs Dermatol. 2017;16(12):1262-1266.