Leak-proof closure for drinking bottles. The Sigg WMB One Top closure is the perfect 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 always protected from bacteria and dirt for hygienic use. The screw cap is, of course, BPA-free and contains no harmful substances, including phthalates or estrogen-active substances.