Well-built strong heavy-duty metal with equally durable plastic components.
It folds down to an extremely compact size with a good compact carry bag for easy packing and transport.
It's easy to set up with two button locking mechanisms in the center to spread the legs. The range is about 11 inches to just under 18 inches so be aware that there's a limit to how wide you can spread the legs.
There's a sturdy snap lock with numbers on each leg to make sure you're extending them evenly and holding them in place. Each end also has a locking mechanism to help fit it to the feet of your specific tripod. A hand screw helps hold the foot in place to prevent any kind of wiggle or drift. I tested this unit with my SmallRig AD-Pro8 FreeBlazer taking off its flat feet.
The rubber wheels help smooth and quiet the movement. I tested this on less-than-perfect 90-year-old hardwood floors. The wheels themselves were quiet but the floor had a few creaks and I could hear a bit of a rumble when I trucked it. It's certainly a lot quieter than plastic wheels would have been though.
The braking mechanism holds the wheels perfectly still preventing accidental role. It's easily activated with your foot. Unlocking it took a little bit to get the hang of it and wear work shoes you don't mind scuffing the surface when you unlock. In other words, don't use dress shoes if you're using this on a wedding shoot.
The only wish is that there was an angle lock for each foot so you can execute a repeatable arc. While you can certainly execute a decent arc manually but it won't be repeatable and the wheels might swivel around impacting the results.
While many untracked tripod dollys are only good for quick relocation, and this can certainly serve that purpose but the movement is steady enough with minimal jitter allowing you to use it for recording dolly shots as long as you don't need perfectly repeatable movement. While it's not going to replace a tracked dolly this is a great dolly when tracks aren't possible and you need to follow a subject or move around while recording.