The NiSi 52mm adaptor for NiSi 100mm V5/V5 Pro/C4 permits the use of 52mm filter thread lenses to be used with the NiSi 100mm V5, V5 Pro or C4 Holders. It features a lightweight, aluminium-alloy construction that has a corrosion-resistant, black anodized finish for durability.Another great point is the use of high quality aviation aluminum which weighs less, so each of these rings take less room in your backpack and are lighter to carry.