Check out pumptoys.com. I have their STJ original model (based on early Sun Tea Jar homemade units) and it does an amazing job on balls and cock, which fit unconstrained inside the jar. But, if you're like me, vacuums over about 5 mmHg get really uncomfortable for balls - but it doesn't take long for them to get as big as oranges ... or grapefruit if you stay in longer! But it looks like the newer version of the STJ is on backorder.