This vocas 15mm rail support 0350 0310 is used to support higher dslr style cameras such as the canon eos 1d or cameras with a vertical handgrip and allows for attaching 15mm accessories note the 15mm of this rail support will not reach the standard height of 85mm from the centre of the lens due to the camera being higher this means hen using this rail support other accessories need to be height adjustable each 15mm rail is 210mm in length