This “T-Ring” will couple your Mirrorless Camera to any T-Threaded Mount. The thread on this ring is Female 42mm (.75). Note that T-Rings for Mirrorless models are actually tubes, rather than rings. This is to make up for the shorter light path within a mirrorless camera. The reason is all T-Ring/Camera combinations must reach focus at the point to meet the “T2” standard. The T-Ring length is determined by the internal Flange to Sensor distance of the Camera. We also make special short “T-Minus” Rings for some mirrorless cameras (which can be a big help when you have limited back focus).