For the Canon EOS D30, D60, 350D, 400D, 10D, 20D, 30D, 40D, 50D, 5D/ Mk II, 1D/ Mk II/ Mk IIN & the 1DS/ Mk II. This allows operation of the viewfinder without the needing to press closely to the back of the camera & is more comfortable to use. The viewfinder extender also reduces the image size, which can be useful in assisting composition. Please note: this will not fit the EOS 450D, 500D or 1000D.