I actually prefer this top than the Sigg sports bottle top. You can add a clip to the top and makes it easier to carry your bottle around. It keeps your water air tight inside.
Great durability and functionality with the SIGG bottles. However, it tends to be difficult to screw into the bottle. You have to mess with the positioning of the top before you can start to screw it in otherwide you cross the threads and you'll never get it screwed down. A little more effort in R&D could have solved this problem.
It is much better than a metal top which has a awful taste
p. s. I almost gaged from the bottle water