Yes, they are going to be made for glass or acrylic. The 4" Portal is priced at $65. The 2.5" is less, and the 6" is still being determined.The 4" has a focal range of about 18", while the 6" will reach to 34" away. I personally asked about getting one that is like a bi-focal, where I can put it on the front of my new tank to watch hermits duking it out, then slide it up to see some SPS 30" away. It'll cost more, but it would probably be the best option for my system.
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