PLATYPUS Push-Pull Cap, 2-Pack

I wasn't going to write a review on this small piece, but I think some people might be confused about how to install this properly. It should not come off easily at all. It took me a few tries to kind of figure it out after looking at a YouTube video. I think Platypus should really include instructions in the packaging.I added some customer images to show how it is supposed to be installed.I have the  Platypus Big Zip LP Reservoir  (3L), which has a Platypus Hyperflow Valve (the mouth piece) on its tube.1. Remove the valve (mouth piece) from the tube.Yep, it can come off -- just pull on it and slide it off (there is an "inner" tube it goes over).2. Push the valve (mouth piece) into the cover (the small piece with the hole) as far as you can.Note: I found that when the "band" that connects the two parts of the cover is on the bottom (with the valve clear "slider" in the "drink" position) it closes better than when it's on the top.3. Slide the "combined" cover and valve (mouth piece) back over the inner tube while making sure the cover isn't much further behind than the valve tube.This is the hardest part. You'll spend more time pushing the valve (mouth piece) back than the cover. Note: It is hard to push them all the way back without making the cover go much further behind the valve tube (you don't want that to happen). With the cover now covering the valve tube ensuring a tighter fit, being only a few mm off is still good enough of a seal around the inner tube to ensure it won't slip off or any leakage.I promise, it really works great once you get it installed correctly.

I bought this product because of a problem I had while hiking in Nepal. We came around a corner early in the trek and there was our first view of Everest. I threw my pack down and started taking pictures. When I picked my pack back up the bite valve on my Platypus bladder was dirty. The trail there is constantly walked by porters in bare feet and Yaks and Zaks and their droppings. No wonder that I got sick shortly after that.In the US you would think that the trails would be cleaner but frankly it is dirt and it is trod upon by hikers, horses, dogs and cattle. I bought this product to keep the bite valve clean. It does that admirably. It is however rather larger than you would anticipate so it was with some minor trouble that I was able to get it through the little opening in my backpack for hydration. Once it was pushed through I just seldom took it off.

It is a good fit for the bite valve. As someone else had said, it is not intuitive how to get it onto the bite valve, but after I googled how to do it, it was easy. You pull the two pieces of the bite valve apart, then can put the cover on. After getting the cover on, push the 2 pieces back together. I have a platypus 1L so it does make the profile of the bottle rather tall, but in planning for a long trip, the collapsing ability will be great and the cover should work well.