Leak-proof cap for drinking bottles. The Sigg WMB One Top cap is the ideal addition for all Sigg wide-mouth drinking bottles. It impresses with its simple design. With the One Top, the drinking bottle can be operated with one hand: this applies to carrying, opening, drinking, closing, and securing the bottle. Additionally, the mouthpiece is protected from bacteria and dirt at all times for hygienic use. The screw cap is, of course, BPA-free and contains no harmful substances, including phthalates or estrogen-active substances.