Commercial saline sensors
Here is a list of links to commercial saline based EEG sensor systems.
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BRAIN-TRAINER TC26
This is a saline based cap system that uses conventional cup electrodes, covered with a sponge material. Cap material appears is cloth covered neoprene-foam based. Electrodes are inserted in plastic holders with sponge.
https://brain-trainer.com/shop/products/caps-sensors-supplies/
https://brain-trainer.com/product/tc26-s-trainers-cap-kit/
https://brain-trainer.com/product/tc26-trainers-cap-bundle/
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FREE-CAP
This is a variant of the 'European net and post' shown below. Instead of using a post system, the Free-cap has holders for small saline sponges. Both two channel and more channel versions are available.
https://www.neurofeedback-partner.de/product-161.html?language=en
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EUROPEAN NET AND POST / MINICAP
This is an example of the European system mentioned on the main velcro saline page.
http://www.pamel.hr/index.php/en/proizvodi/eeg-kape-elektrode-pribor
This sensor design originally came from Europe, but it is also in wide use in Asia. You purchase the set of sensors along with a 'cap' system consisting of left / right 'endplates' with holes, and elastic straps that stretch between plates across the 10-20 lines. Usually a chin strap is also used to hold it all down.
The sensors have a felt pad that stretches across the top of a flat round screw post (kind of mushroom shaped), held on by an o-ring. You moisten the pad with saline solution, then tuck under the corresponding strap at the desired 10-20 position. Lever-action holds it down in place on the skin. The older style uses the lever action. Newer 'Comby' electrodes just have the a ridge in the electrode holder that mates with the bands.
Some practitioners still use paste or gel with these pads, but I think saline solution is more widely used.
Recently STENS Corp. here in the U.S. is now carrying this a similar type of headset, they call it Minicap.
https://store.stens-biofeedback.com/products/nx-minicap
This can be used with their Minicap electrodes, by placing a small sponge soaked with saline, under the electrode.
https://store.stens-biofeedback.com/products/el-tp-minicap-electrodes
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GREENTEK
Greentek has a range of electrode caps, incorporating saline sponge holders.
http://www.greenteksensor.com/
It's possible that OpenBCI may be offering a variant of this in the Shop in the future.
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OPEN FOCUS
Another historical system from the U.S. was that developed by Les Fehmi in the 1980's for his 5 channel Open Focus synchrony device. This has 5 fixed position sensors (Fpz Cz Oz T3 T4) on an elastic band with velcro closures. More search results on the synchrony training.
Elastic bands and conventional velcro is used (not One-Wrap), so the positions / pockets are fixed to the five 10-20 sites mentioned.
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FLEXTRODES
http://bio-medical.com/products/flextrode-package.html
http://www.futurehealth.org/bm_flextrodes.htm
FLEXTRODES consist of a hollow, screw-like plastic retainer containing a felt wrapper that encloses a standard gold cup electrode. They are used with a retaining ring that can be inserted in a headband, hat, or other holder.
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FLEXCAP
http://www.futurehealth.org/bm_flexcap.htm
A similar system to Flextrodes, with a locator cap containing holes for all 10-20 positions.
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GEODESIC SENSOR NET
http://www.egi.com/clinical-division/geodesic-sensor-nets
On the high end, Geodesic Sensor nets also use saline silver chloride sensors. This mesh is dipped into a bucket of saline solution. Then the net is pulled over the head and sensors are individually wiggled to contact down on the scalp. However this only comes in large channel counts, 32, 64, 128, 256.
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EMOTIV EPOC
The Emotiv EPOC is a saline system. I'm not sure what metal is inside their connectors, silver or gold? They have female sockets on the headset that accept little felt cylindrical pads that slip into the sockets. Pads are then moistened with saline before each use. They do sell kits with more pads, so I understand these wear out over time. I've also heard their users on forums complaining that the felt pads fall out or can be intermittent. Maybe they have solved this.
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NEUROBAND
Diane Stoller developed a velcro based system by hand sewing the straps out of separate hook and loop material. However this substantially drives up the cost, in terms of additional cost per strap. The Velcro One-Wrap tape we suggest, essentially does the same function as these straps, but with no additional cost per strap. (Once you have purchased the $10 twelve foot roll of 3/4" strap material.)
http://www.drdiane.com/product-category/neuroband/
For the sensor pockets, Neuroband uses actual animal skin chamois material, instead of the better performing (more absorbent) micropore cloth chamois we are using. The cloth also I feel can be more easily cleaned, and does not have the organic skin pocket cellular structure of dried out skin to deal with.
She does sell a silver chloride type of button snap, however the button is not replaceable (it is sewn to the chamois), thus has high replacement cost of $10 each.