Hō and Ban

and are child-like twin Bounts who work together telepathically and use their dolls (Hō controls Guhl and Ban controls Günther) to manipulate water. They attacked Karakura Hospital in an attempt to kidnap Uryū Ishida. They were defeated by a combined effort from Noba (whose plush form at the time afforded him immunity against the Bount Doll's power) and the newly arrived Ganju Shiba. After Noba used repetitive short distance teleports to knock Ban unconscious, forcing Hō to control both dolls simultaneously, Ganju destroyed their dolls with fireworks, killing the twins as a result.

Dolls
and are Hō and Ban's twin dolls, respectively. Both dolls take the form of bottlecaps. When released, the dolls can control water, making destroying them quite difficult since the bottlecaps are small targets within the large eyestalk-like shape they take. In order to kill opponents, Guhl and Günther form a large stalk around their enemies and restrain them, forcibly drowning them. They also have the ability to force themselves into the human body (as 70% of the human body is water) and tear the enemy apart from the inside out. They are stronger when more water surrounds them. Each control one doll, but both of them can apparently control either if need be, as Hō demonstrates. Ban and Ho can control the dolls to a more devastating degree by merging their large bodies of water. But the downside is, Ban and Ho need to be side-by-side with each other in order to coordinate properly the doll's attacks; the twins being more than a few feet away from each other would result their concentration (which is synchronized via something like telepathy) getting broken off. 

Trivia

 * They are the ninth and tenth strongest Bounts in the group.