Amazon.com : The Flash X-Tender (Better Beamer) FX-4 Flash Output Booster for the Nikon SB-600 and SB-800 Flashes with Lenses 300mm : Camera Flashes : Electronics
Amazon.com : Nikon SB-800 AF Speedlight for Nikon Digital SLR Cameras - Old Version : On Camera Shoe Mount Flashes : Electronics