Passive Electrodes

Hello,
I've been working on building a Modular EEG device. Right now I'm trying to
decide what to use for electrodes.

My main question is this: what is the difference between the detachable
disk leads and EEG single disk electrodes on the Electrode Store? (
http://www.electrodestore.com/index.php/eeg/eeg-electrodes/detachable-eeg-disc-electrodes-and-leads
 and
http://www.electrodestore.com/index.php/eeg/eeg-electrodes/eeg-single-disc-electrodes,
respectively). Why are the single disk electrodes so much more expensive?
I'm leaning towards using the WBT-DSCs, are they reusable? I've found them
on some other sites that seem to indicate they are disposable.

Thanks!
Herb Susmann

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