Mamiya C330 Focusing Screen #5 (Crosshair)

Description

This is a very interesting focusing screen for the Mamiya C330, it has no fresnel and the focus aid is just a cut out of the ground glass in the middle of the screen, where a virtual image appears. You move your head back and forth to see the difference between the virtual image and the cross, and if the image moves with respect to the cross, the image is not in focus. If there's no movement, it's in focus. See page 21 of this pamphlet for details:
https://www.pacificrimcamera.com/rl/00330/00330.pdf
Unlike literally every other focusing screen for Mamiya C330 on eBay, I have actually tested this one in my camera, and it is what I claim it to be.
It's honestly easier to do than the description implies, and was made for super precise macro focusing but I could see it being useful for others too. Fits only in Mamiya C330 and C330F, not C33, C3, C2x series or C330S.
This is only the screen, not the screen-in-a-metal-frame, so they are not "quick-swappable" but they are easy to change. Message me and I can help you do it, if you want.