Reefer
A Reefer is a refrigerated ISO shipping container with self-contained refrigeration machinery, used to transport temperature-sensitive cargo — fresh produce, frozen foods, pharmaceuticals, dairy, meat. Standard sizes are 20'/40' (and 40'HC), with the machinery occupying one end of the container.
Reefer containers require electrical power to maintain temperature: at sea, they're plugged into the vessel's reefer sockets; in port and on rail/road, they need power generators or genset attachments. Temperature is set in advance (set-point), and most reefers can log internal conditions for the entire transit.
Commercial considerations: reefers cost 3-4x dry container freight per slot; they generate continuous demurrage if dwell time exceeds free time (refrigeration costs power); and they have higher detention rates because empty reefers are scarcer than dry containers.
A reefer is a container that carries its own climate — and its own cost. It needs continuous power, costs several times dry-container freight per slot, and racks up demurrage quickly (refrigeration burns power), so managing power, set-point and dwell time is where reefer economics are won or lost.
What temperatures can a reefer hold?
From frozen (around −25°C to −18°C) through chilled (0°C to 4°C) to controlled-room-temperature (15°C to 25°C) for sensitive pharma — set as a "set-point" and maintained throughout transit.
Why do reefers cost more than dry containers?
They need continuous power, specialised equipment and are scarcer, so freight runs several times higher, and idle time generates demurrage and detention faster.