Each dumbbell is adjustable in 5lbs increments up to 55lbs.
Research Articles:
Salo, P. K., Häkkinen, A. H., Kautiainen, H. & Ylinen, J. J. (2010). Effect of neck strength training on health-related quality of life in females with chronic neck pain: a randomized controlled 1-year follow-up study. Health and Quality of Life Outcomes, 8(1), 48. doi:10.1186/1477-7525-8-48
Tsolakis, C. K., Vagenas, G. K. & Dessypris, A. G. (2004). Strength adaptations and hormonal responses to resistance training and detraining in preadolescent males. Journal of Strength and Conditioning Research, 18(3), 625-629
Adjustable in 1lb increments up to 40lbs.
Research Articles:
Hakestad, K. A., Torstveit, M. K., Nordsletten, L. & Risberg, M. A. (2015). Effect of exercises with weight vests and a patient education programme for women with osteopenia and a healed wrist fracture: a randomized, controlled trial of the OsteoACTIVE programme. BMC Musculoskeletal Disorders, 16352-360. doi:10.1186/s12891-015-0811-z
Hodgetts, S. s., Magill-Evans, J. & Misiaszek, J. (2011). Weighted Vests, Stereotyped Behaviors and Arousal in Children with Autism. Journal of Autism & Developmental Disorders, 41(6), 805-814.