You're correct @jakedduck1, the RestoreX device was originally developed to treat penile curvature due to Peyronie's disease. It works by applying gentle, dynamic pressure to stretch and shape the penis. The length gain is in part due to curvature correction. Research is now being conducted to see if the same approach could be used to improve penile form and functioning after prostate cancer surgery. Here's an article about a preliminary study:
- New device helps restore penile length and sexual function after prostate cancer surgery https://www.newswise.com/articles/new-device-helps-restore-penile-length-and-sexual-function-after-prostate-cancer-surgery

And the full study
Efficacy of a Novel Penile Traction Device in Improving Penile Length and Erectile Function Post Prostatectomy: Results from a Single-Center Randomized, Controlled Trial https://www.auajournals.org/doi/10.1097/JU.0000000000001792