Shimano has added a new rotor option to their lineup, the RT-MT905, which allows riders with 6-bolt hubs to take advantage of the heat dissipation technology that was previously only available in a Centerlock version.
The Ice Technologies Freeza design consists of a layer of aluminum sandwiched between two outer steel layers, with a portion of that aluminum extending below the steel layers to act like a cooling radiator. Compared to stainless steel rotors, Shimano claims the IceTech rotors allow brake pads to last 10% longer, and create a 150°C (270°F) overall temperature reduction.
When the rotors become available in early 2022 there will be 180mm and 203mm versions. Shimano did release a 220mm stainless steel rotor a few months ago, so I wouldn't be surprised if a 220mm version of the RT-MT905 gets added in further down the road. For now, Shimano says that the heat dissipation benefits of IceTech make it possible to avoid going with larger or thicker diameter rotors.
The 180mm version is priced at $85.99 USD, and the 203mm version will retail for $94.99 USD.