[Hasselblad X] For a person who hates the inconvenience and expenses of having to have all sorts of ND filters in different sizes this product is a Godsend. 
The filter is built into the adapter, and placed at the back, between the back lens element and the sensor. It works great! Besides providing the ability the throttle ND gives you to shoot at the aperture of your choice in bright sun light, the filter provides the added benefit of protecting the sensor when you change lenses. So, no more worries about buying all those ND filters in different lens sizes. The throttle ND adapter works for all your lenses of that mount type. Highly recommended.

[Hasselblad X] This adapter works great with both of my Sony cameras. My old Pentax 645 lenses have a new life! The tripod mount on the adapter is a plus as it takes astrain off of the camera tripod socket due to the weight of the medium format lens. The corner to corner sharpness will jump out at you when using the 645 lens with a full frame or cropped sensor.

[Hasselblad X] Not sure if the other bad reviews are due to user error, but I’ve had zero issues with this adapter. I use it with a Pentax 645 75mm 2.8 lens with my GFX 50S. The images are excellent. There is no vignetting on the corners with the 75mm lens. I’ll soon be trying it with the Pentax 645 45mm 2.8 lens. It connects to the Pentax lens nice and snug. And it connects to the GFX body totally great.

You have to change a setting on the GFX to shoot without a lens because there is no electronic communication between the lens and body. With this specific adapter, the f stop is changed on the adapter and not on the lens, even if your Pentax lens has the aperture ring on the lens itself. There is no clicked adjustment of the f stop on this adapter. It’s smooth as you change the f stop on the adapter. So if the lens isn’t wide open or stopped down completely, you’re pretty much guessing what your f stop is. Not too big a deal to me. The ring to change the f stop is nice and smooth. The build quality is very good.

The main advantage is you can add wonderful Pentax 645 lenses to the amazing GFX cameras. Pentax 645 lenses are pretty darn cheap on eBay.

[Hasselblad X] This adapts my 110mm f/2 FE lens perfectly to my Pentax 645d. I imagine it would work just as well on the 645z.

[Hasselblad X] Arrived early - Works perfectly with all three Pentax 645 manual lens I have on Sony A6000

[Hasselblad X] I just received this adapter. Fit is excellent on camera and lens. Mounted my 75-300mm AF Nikkor and took some fun shots while waiting to get the kit outdoors.
ND filter is very smooth. Definitely recommend this adapter.

[Hasselblad X] Great seller. Fast delivery. A

[Hasselblad X] I purchases this to be able to use older 645 Pentax lenses on a Fujifilm GFX body. It works just fine. I like the tripod quick release mount and the aperture adjustment one the mount.

[Hasselblad X] Just wanted to say thanks to b&h group for helping me with this first.
I got a fujiflim xt3 and the adapter fit well and well constructed. At the beginning couldn't take pictures but it was a setting in the camera.
To new buyer of the product remember all focusing are manual since is a not electronic adapter but for was is worth is great
Thanks again b&h

[Hasselblad X] High Quality - High Value - Great Service - Amazing Results.
I receive it and notification from B and H let me know that the product I was intrested in was on sale. I took advantage of that and have to be special ordered and it arrived a week earlier then anticipated.
The product is awesome!
I am a very satisfied customer!