54mm Hard Lines have a 34mm width and a 23mm ... less drag and longer grinds. These 56mm wheels have 32mm width and 16mm riding surface. Similarly are the V5 Sidecuts in Bones' original formula.
At 54mm, the rims are quite a bit deeper than most gravel wheels on the market, which tend to top out around 40mm. Still, with a weight of just below 1500 grams, the depth comes with little penalty.