A description is given of refrigerators in which the superfluid ⁴He is entering through superleak. These are, for example, the vortex pump refrigerator and the ⁴He-circulating dilution refrigerator. Although these are rather different type refrigerators, the superfluidity of ⁴He plays an essential role for their cooling principles and operations. The view point of superleak-operation will make it much clear.