RayFlash introduces universal Ringflash adapter with new clamp design: Digital Photography Review
Coco CR-580 Ring Flash Adapter Rig for the Canon 580EX II External Flash on the EOS 70D, 60D, 50D, 40D, 30D, 20D, 10D, 5D & 7D (MK I & II) DSLR Cameras -
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Ray Flash 2 Universal Ring Flash Adapter review @ PHOTO-TIPS-ONLINE.com