How to choose muffle furnace?

Temperature

1200℃, 1400℃, 1700℃, 1800℃

Chamber size

1L(100*100*100mm), 4.5L(200*150*150), 12L(300*200*200mm) and 36L(400*300*300mm)

Note

If the equipment needs to feed inert gas, need to choose an atmosphere furnace