This is an easy to use device. Adjusting the cup circumference is as simple as turning the base while the clamps spiral in or out around the base of your cup, and then setting a thumb screw to hold it in place.I like that the variable speed is not pre-sets, but totally adjustable, which allows to stir slowly which is good to avoid bubbles, however, if you stir too slow, there is no agitation in the center of the pool and it will remain unmixed even though the outer pool is thoroughly mixed. Increaseing speed or possibly mixing a larger volume should fix this, or..., I'm thinking of cutting a section of one stick and hot gluing it to another to make an "L" shaped stir stick that would cover the full radius of the bottom of the container. doing this, one should be able to go very slow and thus get back to the agenda of fewer bubbles.The unit is sturdy and feels solid, like it is well built.The cord is stingy short, for the dollar spent on this specialized item, the cord should have an extra two or three feet -- some may view this as a plus if having a tight workspace with outlets nearby.The horizontal bar which holds the stir stick cannot be adjusted up or down, but the stir stick inserted into the slot can. Still, this is a limiter if wanting to use a 8oz cup or smaller and a popsicle stick -- you are stuck having to use the large stick as the small stick wont reach the bottom of the container - this is only an issue if doing small amounts.An excellent product I would buy again.