I purchased this ultrasonic cleaner to clean the gunk out of watches and jewelry.  I was looking for something that would be more powerful that the "toys" that are for sale for under $30.  I just do not feel that they have the overall horsepower and cleaning ability based upon prior experience.  I found this one, and it is quite large and appears to be the most powerful cleaner in its class.  I am extremely pleased with the purchase.  Rings and watches come out looking literally brand new and fresh from the factory.  The only downside is that it is clear that the instructions were not written by a native english writer, so the grammar leaves a bit to the imagination.