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 ```I thought it would be 'cool' to be able to talk with my SO while zipping around in my B, so I built a windblocker to fit behind the seats, just like I saw at a couple of web sites and in a BMW M-3 this a.m. on the way to work. If you have done this or understand aerodynamics better than I continue. If not, continue at your own risk. So I made a plexiglass (perspex for you Brits) shield, mounted it on a tonneau bar and went riding Sunday to check out version 1. Now, the shield sits a good 12 inches behind the seat (~30 cm for you Brits) and is strictly vertical. The distance behind the seat is a function of the tonneau bar. The shield reaches about 1-2 inches (2.5-5 cms for you....) above the seat. Observations: At 65-70mph (100-112 km/hr for ...) I noticed the wind rustling the top of my hair in a more completely front-back direction than in a swirl, but other than that, not much change in the wind torrent. Questions: 1. In all the commercial versions of windblockers, they sit only a few inches (a few more cms...) from the back of the seat. In the BMW I saw this AM, that was a bit less accurate but that shield was tilted forward so the top of the windschield (made from screen by the way) was very close to the seat. Is the distance from the shield to the back of the seat important? I would think so, but I'm surprised that 12 inches (30 cms) would matter that much. 2. Does the height of the shield above the seat (or head of driver) matter? This question probably requires an experienced-based answer because if the shield is too high, then it interrupts the flow of the air from the windshield over the cockpit (which would defeats the windblocker's purpose) and if not high enough, does not block the recirculating wind. 3. I've seen both plexiglass and screen windblockers. Does it matter??? Any comments about which works better? TIA for any learned or experienced answers, Bill S. '76B BMCSNJ ```