My wife is 5'1" 110 lbs size 4. Our girlfriend is 5'6" 140 lbs size 8. We are looking for advice on a strap-on they can use on each other. My wife thinks she wants her harness to vibrate when she is screwing our girlfriend. The girlfriend is not sure if she wants a vibrating harness or not. We have never tried this before and would like to ensure a good time as soon as possible rather than trying a bunch of stuff that will not be any fun. A quality experience will be the priority, cost will be considered second. Do we need a different one for each lady?? We were thinking so, because my wife is so little. We appreciate any advice including specific brands or models that have a proven track record. Are there any videos that help us have a better experience?? A "how to" or " strap-ons for dummies"? Thanks!