The first thing to pay attention to is the size. There are many kinds of luggage sizes, ranging from 16 inches to 30 inches, which can be selected according to the number of days of travel. It should be noted that if you need to travel abroad, according to IATA regulations:   Size of portable case: the sum of the three dimensions of length, width and height shall not exceed 115cm (generally 21 inches);   Size of consignment box: the sum of length, width and height shall not exceed 158CM (generally 28 inches);   If the sum of the three sides exceeds 158CM, it needs to be transported as goods.   It will be easier if you only travel in China:   Dimensions of carry on luggage: length, width and height shall not exceed 55cm, 40cm and 20cm respectively;   The size of checked baggage: the sum of length, width and height shall not exceed 200cm;   For some low-cost airlines, such as Chunqiu, the upper limit of carry on luggage and checked baggage will be smaller. If you travel in these ways, you need to pay special attention.   Therefore, we say that the size is not necessarily good. When the box is large, you have to check it, and you have to wait in line for luggage. Waiting in line for luggage means that the car that picks you up has to wait for you, and the luggage you finally get may be broken by violent check-in.