Sea & Sea viewfinder for Nikonos

Hi

I am looking at getting a 16mm Sea & Sea wide-angle adapter
(secondhand) from my local uw-photo shop for my 35mm lense (on a Nik
5).

I will of course need to buy a viewfinder for this, there seems to be
two different Sea & Sea models to choose from, the current one on their
website (with line markings on the glass for various lenses and a wheel
to lock it to the camera body) or what I presume is an older model with
plastic masks and a wheel to adjust for distance (not sure if this
locks to the camera body??).

Was the older model replaced for good reason or will either be fine; I
am able to get the older model secondhand with the lense.

I would appreciate your input.

Regards

David