Does this work with the K400?

The one I received wouldn't pair with a k400r keyboard, but did pair with two different k800 keyboard and m310 mouse. I used the unifying software which does see the unifying receiver but would not detect the k400r although two other unifying receivers would. Needed to swap the receivers around to get all devices working.

will this work with bluetooth headsets

No, this is not a bluetooth device.

Will this work if I am trying to utilize 1EA wireless KB and Mouse with 2 different PCs?

If I understand your question correctly, you want to use one keyboard and on mouse on 2 different systems and you want to purchase a second unifying receiver for the second computer. I'm a quadriplegic and I have a desktop at and a laptop for one I am in the hospital or elsewhere. I have just enough movement in my columns to run a trackball and I have a helper who can type on the keyboard, when it is necessary. I have defined receiver on each computer. I use an M 570 trackball and K 800 keyboard, both Logitech of course, and both specifically designed to be compatible with the unifying receiver. In the beginning, I simply swapped the unifying receiver from computer to laptop because somehow my second defined receiver had gotten lost. (I should stress that the trackball and the keyboard were purchased couple years ago and, as you know, Logitech has advanced their design in wireless keyboards. Anyway, my equipment from couple years ago ran fine on the desktop and when I switched unifying receiver to the laptop it also worked fine, no problems whatsoever. However, when I purchased the second unifying receiver a short time ago I found that, with my older keyboard and trackball, there was not instantaneous compatibility. I had to go through the setup program and have receiver " recognize" both wireless devices. I don't know if this is just one of the vagaries of my systems for if it carries through to all the new Logitech unifying receiver's. However, I found swapping out unifying receiver was an acceptable task for me. All I had to do was tell my caregiver to move the Logitech dongle from the desktop to laptop, an effort which took no more than 15 or 20 seconds. It is entirely possible that Logitech is dealt with the problem I experienced and that they have eliminated it from the newer hardware and software, however, I can not say so definitively. You'll just have to try it out. I do however feel very comfortable saying that if you swap the unifying receiver from one computer to the other you will probably have no problem whatsoever. If you want to go with a second receiver in your other computer, you just have to try and see the works. I can tell you this much: don't have both computers on the same time. I did that without thinking about it and I can tell you that absolutely did not work. I had to be running one or the other. Now, when I switch from one of the other, I do a complete shutdown of one before I turn the other one on. If I do that, problems disappear entirely. I'm sorry I can't be any more definitive , but that is my experience. I will say this: before I became a quadriplegic Logitech was the only keyboard/trackball, but I was satisfied with. I think they make great stuff , and I'm locked into their equipment. I have thanked my lucky stars that I can move both of my thumbs enough to run a trackball, because their design is perfect for me and my physical capabilities. I am on my computer as much as 10 hours a day and have been for years. All I can say is, I have never had a significant, much less a difficult problem with Logitech equipment or software.

Brand	Logitech
Product Dimensions	1.91 x 1.52 x 0.64 cm; 9.07 g
Item model number	LGH_C-U0007
Manufacturer	Logitech
Series	C-U0007
Color	Orange
Power Source	Corded Electric
Operating System	Chrome OS, Windows 7, Windows 8 1
Are Batteries Included	No
Item Weight	9.07 g

Logitech Logitech Unifying receiver for mouse and keyboard

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