Not every client needs the same amount of lift, and the right height often is not obvious until they have used the bathroom a few times. An adjustable raiser lets you set the height after the assessment, change it as strength returns, and settle on what actually works in practice.
That flexibility is useful post surgery, when a client may need a high seat for the first six weeks and much less after that. It also helps in shared households, where one setting has to be a reasonable compromise for more than one person.
It fits over the existing pan, so there is no plumbing work and nothing permanent about the installation. For rental properties and supported accommodation that usually decides it.
