This is a smallすり鉢 (mortar and pestle) from Studio M. It's perfect not only for grinding, but also for serving dishes like goma-ae (sesame dressing) for 1-2 people. The dimensions are approximately 11.7cm wide and 4.5cm high (outer measurements). I've used it a few times. Since my family has grown, I don't use this mini size as often, so I'm hoping someone else will.