The speed bonus for every ring is random. It can be as low as +4 or as high as +28. Outside of the guaranteed speed boost attribute, it functions as an ordinary ring (i.e. no DV/PV values, can turn out to be great/miracle/godly).
They are not unique items and can be often found as drops from NPCs (especially NPCs with many ring slots, like those in the Yith race), in dungeons, as blackjack rewards, treasure ball, and bejeweled chest prizes. They can also be wished for and given as a reward for Hunting quests. Moyer the Crooked can sell these if his shop rank is high enough.
One is guaranteed to appear in the Pyramid.
Speed rings remain mostly the same as in Elona. However they now have a unique sprite; base color is blue-ish, but it can vary depending on material.
Speed rings are also one of the few pieces of equipment with an innate speed boost (the others being shoes and, rarely, non-unique artifacts). A nice trick to increase speed quickly is to use scrolls of inferior material on rings you don't need, until they come out as made of raw/candy, then eating them to train speed.