Sturdy and substantial
The BG Pro's grip is big and comfortable enough to counterbalance a fairly weighty lens when shooting handheld.
Software
Because the lens images upside-down, you need to use software that can flip it. Or shoot that way.
Many parts
The rig consists of two pieces, and the separate DOF (depth-of-field) Adapter is a few pieces itself.
Mounting
There are two standard 1/4"-20 screw mounts on either side.
Assembled
This is what the rig looks like assembled but waiting for a phone, and with the macro lens in the mount.
Grip
The grip on the BG Pro equipped with the DOF Adapter.
Bottom
The bottom of the right half of the rig.
Grip only
If you just want a substantial grip for holding the phone to shoot handheld, you can use the right side by itself.
Beastgrip Pro
A spring-loaded clamp holds the phone in place. You can also tweak the location of the jaws by moving them to adjacent screw holes.
DOF Adapter
The Adapter awaiting a lens.
Left side
The rig with the DOF Adapter, from the left.
Bottom
There are three 1/4"-20 mounts on the bottom.
Equipped with phone
The BG Pro with an iPhone 6 Plus in it.
Front
The view from the front, with the 10x close-up lens.
Lens mount unit
The two rails slide into the right half and you secure them with two thumbscrews.
Empty mount
The naked lens mount. It has brass threads.
EF mount
The DOF Adapter has a Canon EF mount.
Focusing screen
The focusing screen sits between two other rings, and making sure that it's level as you rotate all the different tubes can be trying at times.
DOF Adapter, disassembled
From left to right, the Adapter consists of a 10x macro 37mm-to-52mm converter, focusing screen sandwiched between two rings, and the EF mount tube. A 37mm 10x close-up lens goes on the mount between them.