This tool proved to be too fat to get past the permanent metal cross-hatching in my kitchen sink's drain. Although the Sweep is much more slender than the average plumber's snake, it was not slender enough to make it past this impediment.
I then tried it out on my bathroom sink. I have an older style of drain stopper here. This metal stopper plug can be removed. However its raising and lowering motion is controlled by a horizontal bar that is nested a few inches below the drain opening. I was afraid the Sweep once again wouldn't be able to make it past such an impediment. However it did. But this time, the existence of this horizontal bar circumscribed the movement of the Sweep snake to such an extent that I wasn't able to maneuver it into or past the P-trap of the pipe under my sink. Therefore once again, the tool proved useless.
The instructions on the Sweep's package say that if one has this problem gaining access - one should disassemble the pipe at the P-trap and work from there. But that's exactly why I bought this tool - to AVOID having to disassemble and then re-solder pipe!
Also, the handle of the Sweep is made of rather flimsy plastic and arrived partially broken. The breakage did not materially affect the operation of the unit, so I'll probably keep it and find some use for this tool someday. But I cannot recommend it. Before you buy it, check to make absolutely sure that your drain will allow access to a snake with a girth actually somewhat over 3/8 of an inch.