These are the general terms for the trucking industry.
53' foot trailers are the maximum length allowed without an oversize permit. In metric these are 16.2m; however, the industry measures trailers in feet.
48ft (14.6m) was the previous standard, and there are still many of these trailers in use.
Sleeper birth trucks have a sleeper birth unit directly attached to the cab of the truck. These types of units are used to transport freight & services usually beyond 100 miles (160km) of the home terminal. For over-the-road truck drivers, these sleeper birth units are equipped with living quarters as well as a bed. Living quarters can include such things as a refrigerator, television and inverter which will give the driver access to plug in microwave ovens, computers and other electric devices.