Rescue from a disabled bell usually involves another bell capable of the same depth. Divers will generally transfer between bells at or near the bottom at ambient pressure. It is possible in some circumstances to use a bell as a rescue chamber to transport divers from one saturation system to another. This may require temporary modifications to the bell, and is only possible if the mating flanges of the systems are compatible. Rescue from a saturation system in imminent danger is generally known as hyperbaric evacuation, and generally makes use of a hyperbaric lifeboat or rescue chamber to transport the divers and a hyperbaric reception facility where divers can be decompressed and treated in relative comfort.