I found that the US Cup was too large for my equipment. More specifically, the throat was too deep for me to feel the deep throat sensation. I only criticize this because the Soft Tube US cup was perfect for me, while the regular had been too small. The sizes on these things are a bit inconsistent. I would recommend the Soft Tube US for a penis 6" or longer, or just pretty thick in general, but to feel the full benefits of the Deep Throat US I think one would have to be about 8".