Stainless Steel Retractable Travellers Cup Keychain (Small/60ml)

Pros: Pretty damn good cup. Well constructed. Six sections (including the base). 60.2 grams / 2.125 ounces, as weighed by my DX digital pocket scale (SKU 1165.) Cinches up tight.
Good for taking medicine on the go.

Cons: Perhaps a bit heavy for a backpacker or camper.
Key chain attachment is kind of useless, given the weight of the cup it would probably fall out of the cover.

Other: For the price, it can't be beat.

Pros: It unfolds and folds in a second so you can have your own portable cup to drink. No more risks for drinking from a cup from someone you do not know, no more going to a party and not having something to pour your drink on ;)
As I said it is very practical, and water does not leak at all if you opoen it correctly.

Cons: It is a little heavy, nothing essential but remarkable, it makes soubnds while in your pocket from the metal rubbing (from the 6 pieces)
Not anything really bad.

Other: Buy it. You will surprise your friends and never be on that moment you do not have a glass to take medicines.

Pros: Segments lock tightly, no spillage of valuable moisture: what goes in cup reaches throat (bad motoric coordination exempted), if you pull open, then twist, while still pulling, to locks the segments in place securely. Merely flicking or pulling open won't do, and I'd not entrust other than rotgut to it when not twist-locked. It seems easy to get the cup filled - people appear to like filling it, only to see it in operation - but that could also be a minus. Key chain attached to the right (cover) side, therefore one can use the cup without dragging the whole keychain with it.

Cons: Wipe dry after cleaning, or limespots will develop, or better, keep in perpetual use - rinse with next drink. Unspecting souls may raise an eyebrow, unless you explain that this is an radiation protection device, to wear on your head. Then they'll raise both. Burrs at bottom plate - had to grind those down to avoid cutting my fingers when twist-locking it. Cup is not strongly held by cover. Don't dangle it from your belt, better keep it in your pocket, to avoid losing the cup.

Other: bottomline: A seasonal gadget, compact enough in its collapsed state to be easily tucked away until next winter.

Pros: It holds water perfectly, and is super-useful for camping/traveling. I was a bit wary of the way the case lid attached (expected it to screw on), but it seems to be working fine.

Cons: It's really small, I have to use it over and over to quench my thirst even a bit.

Other: It's what it looks like, it works how it should, but it's pretty small all the same.