The lady and I bought a Vac-u-lock. Seemed nice enough. A variety of attachments, even a place on her G string type strap to lock on a plug or two. It just seemed to me like it would be more secure than the O-ring style harness's. I couldn't have been more wrong. It was total garbage. We used it once and tossed it out, for a number of reasons. Namely the low quality materials the dildos were made from irritated me; Giving me a border line burning sensation. Plus they've got a monopoly on the dildos because it's there system.. So your forced to use low quality crap because that's what they make. Harness quality was poor. And the Vac-U system itself is a pain. I'm an athletic 180lbs and I had a hell of a time pulling the dildos off the Vac-U prong. Anyways we switched to an Aslan O-ring style harness and now have a seemingly unlimited selection of high quality, body-friendly silicone dildos to choose from. We couldn't be happier, I would never go back. Didn't mean to rant.. but yea.