The opaque closures protect contents from UV light when used with opaque bottles. Reduce chance of cross contamination Opaque white and amber closures protect contents from UV light when used with opaque Nalgene bottles One-piece, linerless, with integrally molded seal ring Fit Nalgene narrow-mouth 125 and 250L bottles Well-defined closure knurl makes gripping and capping easy Guarantee leakproof, when used with Nalgene narrow-mouth bottlesMeer tonenMinder tonen