Optional Rear Antenna for Pro-3700/Pro-3750 (SWRA-37) Part # SWRA-37 Whistler Group Sale! from 9999 /per Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Optional rear antenna for the Pro-3700/Pro-3750 provides additional Laser-Radar detection from the rear of the vehicle. Tweet