I ended up returning it, as it was not necessary in my installation. However, if you do need it, here's some thoughts:

My doorbell is perpendicular to the front door and perhaps 5-6 ft away from the doorknob, pretty close. The extremely wide FOV made angling the Doorbell Pro unnecessary.
The Doorbell Pro allows you to draw on the screen areas where you do not want motion sensor active. This means, you can use these shims to bias the Doorbell Pro towards the sidewalk, and still "zone out" areas that would cause a lot of false alerts (like cars going by on the street). You may also need to buy this to eliminate areas of undesired motion too.

NOTE: photo is deliberately cropped, so you are not seeing the entire frame.

I wish I had known it would be 2/3 the purchase cost to return it. (I should have checked.) I suggest if you are unsure, install the DB Pro for a few days and assess. Then place an order for these shims if you find coverage unacceptable.

Not shown are some screws included. IMO they are long enough for perhaps two plates (30° angle), but not long enough for all three shims (45°). They have some info on how long those other screws would need to be in the package. If you need these shims, oyu will find them pretty much perfect for any standard doorbell swap out.

Finally, please don't poorly rate it of thou bought this for something other than RING Doorbell Pro. It's not designed for other units and they clearly state that.

I put off buying the Ring Doorbell for a long time because my door is 90° from where my doorbell is hard wired. I thought all I would see is the wall directly in front of the doorbell, not the door or the sidewalk coming up the side of the garage. I am pleased to say that with only the 30° adjustment, I can see the door AND all the sidewalk and into the front yard! Easy to mount and seems very sturdy. Looks great! Cheap and simple solution!

Reason for purchase - Camera angle of the doorbell cam was reflecting off the wall when in night mode.

Pros - Fit's Vivint doorbell camera with minor adjustments. Sturdy plastic and gets the job done.

Cons - None so far

Overall - I am pretty satisfied with the purchase and the price. It did not take long to install and with the provided variety size of screws I was able to mount the doorbell camera with no issues.

Installing this box to the brick wall was the hardest part of installation. Even using a masonry bit, it takes quite a while to make holes in our super hard brick. So, I decided to use Loctite instead and simply "cemented" the box to the brick. After that, installation of my Ring Pro was a piece of cake. The smallest angle turned out to be just right to center the view back onto the porch for optimal coverage. Tightened the top and bottom screws and all is set. Now I need to adjust the angle down a bit and have bought the three little boxes for that. Next mini-project.

Works great to give us a better view for our RING doorbell camera. Our doorbell faces a wall without this, so now we have the ability to view more of our yard and further out into our cul-de-sac. We used the 45 degree insert.