Double seal top with dust cap that protects the spout from dirt and leak-proof spout. Made from 100% food safe polypropylene. Transparent dust cap + top fits all SIGG reusable bottles and dust caps fit hinged SIGG kids tops. Also great for adults! Innovative bottle top and inter-changeable hinge dust caps Dust cap keeps spout clean Leak proof with easy close twist spout BPA-free Made from 100% food safe polypropylene Top fits all sizes of SIGG reusable bottles (but dust caps only fit hinged SIGG kids tops) Made with Swiss attention to quality; Thanks to its simple design -- half a turn to open or close -- it is easy for children to use and is one of the few leak-proof sports/sippy spout tops for metal bottles. These caps are also great for adults looking for an alternative to the standard sports cap. Glow in the Dark cap uses a technique that requires very little light and glows very bright. Kids love "em! Top fits all SIGG Reusable Bottles and dust caps fit hinged SIGG kids tops! See all of our SIGG Reusable Bottles. We offer lots of additional info on SIGG in our SIGG FAQs.