the 56x39mm wide 93a nano rats are amazing. The shape is essentially a lock in full. The chonky spitfire style wall of urethane on each side of the bearing seat provides structural support for the 26mm riding surface, making them feel harder/sturdier/less squishy than other dragons, and the slide feels more like a soft slider vs. the skittery slide of the v6,v4, nano cubic or rat bones in 93a. Also the bearings are definitely not center set as powell claims, but they are close enough to center that they don't cone out, unlike rat bones or nano cubics.
edit: you gotta be careful to know which shape you are getting when buying nano rats. Powell released like 4 different shapes at once, all under the name "nano rats".