Made out of aluminium (sometimes carbon fiber), sandblasted,with an applied conversion coating to delay oxidation, these holders fit a standard Paterson 3 tank. They hold 8 sheets of 4x5 film, and need 1 liter of solution. Other configurations (6, 7, 8, 9 or 10 sheets) are possible.

$65.- each, including USPS shipping within the contiguous US.
Payment ideally via Zelle, or Paypal (plus fee)

I've been developing 1000+ sheets with this holder over the years, and have gotten scratch free negatives, even developing, and repeatable results.

Gentle agitation is key, so as not to dislodge the sheets from their position. Some developers, like HC-110 with Kodak B/RA x-ray film, benefit from constant agitation.
Loading becomes quite easy after a few practice runs.