Sigg 3 Stage Sports Top Replacement Part - leak-proof cap for drinking bottles. The Sigg 3 Stage Sports Top cap is the perfect replacement for all Sigg wide-mouth drinking bottles. The mouthpiece can be easily opened and closed with your mouth, making the drinking bottle a great companion for various sports activities such as cycling and jogging. Additionally, the practical screw cap remains sealed at all times, ensuring that the drinking bottle is guaranteed to be leak-proof. The screw cap is, of course, BPA-free and contains no harmful substances, including phthalates or estrogen-active compounds.