I use this to mount my Sigma EM-140DG Macro Ring-Flash to my Canon EF-S 60mm 1:2.8 Macro lens with Canon EOS 7D. All I can say is, it works great for my use - intraoral medical photography.The only qualm I have is that it does not prevent the ring flash from rotating during use. It WILL lock the flash in place to prevent it from falling off, but that's about it.