It has to be thicker than 5 mm because the rubber around the virtual pull buoy is already 5 mm, but interestingly enough QR steers clear of coming right out and saying it is >5mm. At least Emilio is up front. Any ITU guys using VPB technology? I bet not, cause they'd get nailed by the officials, but I may be wrong. Following text from QRoo website:
We all know how pull buoys work when in the pool doing laps and training. The Superfull uses what we’ve patented as a Virtual Pull Buoy (“VPB”). Once you try it, you will understand it. It feels like you are taking a corner at 70 mph, instead of a boat taking a wide turn. Being able to rotate on your axis in the water makes you swim faster, with less effort. What does that mean? It means you burn fewer calories and keep your heart rate lower. It means that you swim with greater economy than without a wetsuit.