It makes the viewfinder readout easy to see even on a bright and sunny day. The plastic piece slips onto the eyepiece of your camera. Prevents unwanted light from affecting your judgment of the image you are producing. Also prevents eyeglass lenses from getting scratched. Makes shooting more comfortable. Suitable for: CANON 22mm EOS 5D 5D Mark II 10D 20D 30D 40D 50D 60D Olympus E-300/330 /400/410/500/510 Leica/PRAKTICA dslr camera Package included: 1 x 22mm Eyecup for CANONUnbranded/Generic