The design is good but would be so much better if made for bigger dicks, My dick gets jammed in there and the motors overheat and burn out despite using lots of lube.

I had to trim the silicon protrusions on the cup so it would not jam so easily. It still jams though. The thrust distance could be longer too.

I am replacing the two weak 7.2 volt gear motors with slower torquier 12 volt ones and power them from an external power supply rather than a battery.

Do not buy unless you have a small dick or it just jams after a while. Annoying when you are close to coming.