Grit Guard makes one idea and makes it properly: keep the grit you just removed from going back onto the paint. The Insert sits in the bottom of a bucket, the Washboard adds an agitation face, and the Dual Bucket System packages the whole two-bucket method.
There is nothing sophisticated here and that is the appeal. A $20 insert measurably reduces wash-induced marring, which is the single most common source of swirls on a daily driver. It is the cheapest correction you will ever not have to do.
The buckets themselves are ordinary; what matters is the insert and the lid. We stock those as separate lines so you are not forced into a kit you half want.