This is a flip-up type sports bottle cap that replaces the cap of a plastic bottle. We recommend this item as it helps you hydrate easily and efficiently without the risk of losing the cap. As shown in the first photo, there are 5 colors: white, red, blue, green, and yellow. We will sell them as a set of 2 in your preferred combination. (However, depending on stock availability, we may not be able to meet your request, so please "always confirm your desired combination in the comments before purchasing." If you purchase without confirmation, the seller will decide the color combination. (Please note that even if you specify your desired colors via the transaction message after purchase, we will not accept cancellation requests if your desired colors are out of stock.) ★Important Notes★ - All items are unused. Please use after detaching the closure on the opening. We also recommend washing with dish soap or similar detergent before use as a precaution. - This product is designed to be attached after removing the ring (part of the original cap) that remains on the bottle body when the original cap is opened, as shown in photos 2-4. If you do not remove it, it may interfere with attachment, preventing the screw from being tightened fully and potentially causing leaks. In such cases, please remove the ring on the lower part of the product as shown in photo 5 (it can be removed by prying with needle-nose pliers, etc.). - The valve does not have a check valve mechanism. If the cap is open and the bottle is tilted or inverted, the contents will spill. - This product is compatible with the standard opening size of plastic bottles (diameter: approximately 28mm). It cannot be attached to bottles with different diameters, or to bottles with the correct diameter but incompatible screw threads. Please understand this in advance. For hygiene reasons, returns are not accepted for any reason. - This is a plastic product. With repeated use, the cap may become loose, or the connection between the cap and the bottle opening may break. Please consider this a consumable item and use it after checking the condition of the product periodically. #waterbottle #canteen #Nalgene #Nalgene #flask #hydration #mountaineering #hiking #walking #cycling #plasticbottle #heatstrokeprevention #ultralight #UL #smartwater #lifewater #SmartWater #LIFEWTR