Actually all their o11 casing is meant for custom water cooling in mind. Air variant is even a plus point for custom water cooling.
Im a big fan of the original o11 in 2016?(Cant remember the actual year) that is the first dual chamber design case. But it has poor use of space. Can only fit 1 miserable 360mm thin rad. And i can still remember the price i paid for it. Over $5xx including shipping. Although the original o11 is mainly aluminium, the case is solid, lightweight, and well painted. The only downside is since it is mostly alu, i have a hard time sticking magnetic rgb strips lol.
Ever since they improved the design with the German youtuber, the o11D came out with impresive use of space. 3 slim 360mm rads was possible. Just a little tight in every corner. Same goes to the air version.
Till they came out the XL variant which is the improved version of o11D in every corners. But they were just tall and big.
But lately they have thought of mini version which when i work with it, i realised they are nice to work with it. One could easily fit an itx to matx mobo and still do custom water cooling with it. Or if you intend to do air cooling, ATX is still possible to fit. They even make the rear inter swapable to shift the mobo up or down to accormodate different thickness of radiators. Now they made an air version for this. Good job Lian Li.