Below is a photograph sent to me today by Andrea Rossi which he describes as the 3 kW E-Cat SKL NGU prototype.
In the interview published this week AR stated that they are currently working with 5 different E-Cat prototypes, ranging from 10 W to 3 kW, so this is the largest one. Looking at this photo, based on the surrounding objects, I’m going to guess the dimensions as being approximately 25 x 25 x 20 cm.