Absorbed Glass Matt (AGM).
The description of the battery mention "immobilized sulfuric acid in fiberglass separator", so I would hazard a guess it is AGM-like SLA battery.
Anyway, the chemistry/construction is not the be all and end all.
Just look at the cycle life vs depth of discharge. That is ultimately what they tested it to do.
In this case, 300 cycles at 80%, with 90% charge capacity retained. So it isn't as good as a GEL battery or top AGM battery, but much better than a standard Lead Acid.