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What are the white rubber condoms? They can be unrolled like a condom. For scale the battery is AA.

  • 4
    Well, have you ever "smeared on" thermal paste with a finger, trying to wash it afterwards? Maybe then you could guess what to do with those "condoms" next time ;-)
    – U. Windl
    Commented May 20, 2022 at 6:35
  • 4
    @Windl no actually, I've always used an included bit of plastic or something like a credit card. This one actually included a plastic spreader tool as well.
    – Ian Newson
    Commented May 20, 2022 at 8:01
  • 1
    I didn't think you were even meant to manually smear thermal paste? At least for CPUs I thought you jut put it on (as a blob / cross / line) and let the CPU heatsink pressure spread it out?
    – Tim
    Commented May 21, 2022 at 13:43
  • pcmag.com/news/… vaguely related
    – Journeyman Geek
    Commented May 21, 2022 at 16:43
  • 2
    @Tim The problem with putting on a centered blob and then press the parts together is that if you use to little, not the whole surface will be covered, and if you use too much, you'll have a real mess wen the thermal paste covers the circuit board. So IMHO "finger smearing" is the preferred controlled way to do it properly.
    – U. Windl
    Commented May 23, 2022 at 6:00

1 Answer 1


You're looking at finger protection, called finger cots, to allow you to spread the material over the heat conducting surfaces and not collect the grease into your skin. Other, medical application uses exist.

Available at Amazon and many online sources. Image below from a non-Amazon site.

Finger Cots

  • 4
    Prior to these, when paste came with instructions, the use of plastic wrap on the fingers was encouraged to fill extrusion grooves in heatsinks that were less than optically flat.
    – mckenzm
    Commented May 19, 2022 at 11:57
  • 11
    They’re also used in food service, where they don’t want a minor accident with a knife to send an employee home for days out of worry over trace amounts of blood. Put a band-aid on the nick and a cot over that to keep water out, then get back to food prep, dish washing, or whatever. Commented May 19, 2022 at 14:10
  • 28
    "and not collect the grease into your skin". Or perhaps it's to protect the thermal paste from the oil on your fingers, which would reduce the conductivity of the thermal paste. Commented May 19, 2022 at 16:38
  • 14
    Back in the old days, you'd use a razor blade or the edge of a credit card, but technology marches on, and neither an electric shaver nor a smartphone is much good at spreading thermal paste.
    – Mark
    Commented May 19, 2022 at 23:54
  • 3
    Also used in watchmaking to keep skin oils off the internals of mechanical watches. The oil can attract dust or dirt which can hinder the inner workings and affect overall performance.
    – dKen
    Commented May 20, 2022 at 4:10

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