These allow you to put smaller or larger filter attachments on to you camera by either stepping up or down the filter size * The first number is the size of your camera lens thread * The second number will be the size of the filter or accessory lens you wish to attach * Made from aluminium alloy. * Suitable for: SLR & Bridge-type Cameras, SLR with wide-angle lens, Medium Format Cameras, Camcorder & Video Cameras and HDV Cameras