What kind of plumbing connection is this?

[wayfun]

I was looking under the sink of my 25RKS this morning and noticed some odd plumbing connections. They look like some sort of quick disconnect. I didn't try to disconnect them because the city water was connected and pressurized. Any idea what they are and why are they used? Here is a photo.

Dennis

[rugerguy]

It is a quick connect,they can be disconected. but sometimes not so easy.I'm finding them more and more on new sink faucets.
I would asume manufactures like them for speed of installation.
Sometimes the will spurt a little water the first time they are preasureized but stop once they are seated.

[Threebutchers]

That's a "take your pick" disconnect....there is a hand tighten compression nut, a threaded nut connection, and a clip pressure fitting....