1. Step up rings, also known as adaptor rings:It allow you to use filters and accessories that are not the same size as your cameras lens. Lenses and filters come in a large range of types and sizes and unfortunately they don't always fit together correctly. Fortunately there is a step up or step down filter for just about any need. 2. How step up rings work:Step up rings provide a way to fit a larger diameter filter or accessory onto a smaller lens. The step up rings screws onto your lenses threading and provided a larger thread with with you can then attach other elements included more step up rings. 3. How step down rings work:Step down rings work in the exact same way but instead provide a way to attach smaller accessories and filters to larger lenses. Step-up Ring Package Included: 1 x 37mm-49mm Step-up ring 1 x 49mm-52mm Step-up ring 1 x 52mm-55mm Step-up ring 1 x 55mm-58mm Step-up ring 1 x 58mm-62mm Step-up ring 1 x 62mm-67mm Step-up ring 1 x 67mm-72mm Step-up ring 1 x 72mm-77mm Step-up ring 1 x 77mm-82mm Step-up ring Step-down Ring Package Included: 1 x 82mm-77mm Step-down ring 1 x 77mm-72mm Step-down ring 1 x 72mm-67mm Step-down ring 1 x 67mm-62mm Step-down ring 1 x 62mm-58mm Step-down ring 1 x 58mm-55mm Step-down ring 1 x 55mm-52mm Step-down ring 1 x 52mm-49mm Step-down ring 1 x 49mm-37mm Step-down ring Specifications: Quantity: 18 Pieces Design: Stepping Rings Kit Compatibility: DSLR Camera Lens Mount Set Size Range: 37-82mm and 82-37mm Functionality: Allows for the use of different filter types and quick release scope ring Colour: Black Material: Plastic Package Contents: 1 set x Camera lens filter(37-82mm, 9pcs ring)