
These are exceptionally handy little double gated carabineers we've found most useful for making quick attachments we hadn't planned on. For example, on our last Appalachian Trail trip I had two of the smallest ones attached to some cordage and stored with our tarp gear. Just in case. During rain in a heavy wind, it was a snap to add those lines to our tarp for extra strength in the wind. When we decided to hang a bear bag to protect our food, another little one made it far faster to attach and detach our bag than tying and untying knots.
I rigged a Tyvek pocket for a hydration bladder for Mudpie's old pack, a medium ALICE on a frame. I used one of these biners to close the top of the bag and to hang the hydration bladder. This made it quick and easy to open the pocket and remove the bladder when we refilled it.
Certainly tying a knot is not an hour's chore. But when you're cold, wet and hungry, and your fingers are numbed to the point they can't handle skinny little rope well, these things are a blessing.
We use the two smallest sizes made by the manufacturer, Nite Ize. There are three larger sizes.
Nite Ize makes a point of stressing these are not mountain climbing biners, nor are they meant to handle the weight of a person.
I bought mine online from the Nite Ize site at niteize and I also bought some at Lowe's.
A warning though. The gates on these are relatively easy to open. I tried using one for my keys and found them coming lose in my pocket.