First of all, I want to talk about the size of the suitcase! Size is the most intuitive feeling of the trolley case, and it is the first point of purchase. When buying a trolley case, 20 "and 24" are often a brain paste. First, let me introduce the selection secret behind the size of the trolley case.   20 inch trolley case, 22 inch Trolley Case   The most common size design of a 20 inch trolley case is 34 cm * 50 cm * 20 cm, which can be directly brought into the cabin. It is suitable for one person to travel for 1-3 days.   The common size of the 22 inch trolley case is 36 cm * 52 cm * 26 cm, and it is not allowed to board.   20 to 22 inches look small. If you don't carry a lot of luggage every time you travel, and you carry some simple daily necessities, this size of trolley case is perfect for you, which is simple, fashionable, economical and practical.   24 inch Trolley Case   The most common size design of 24 inch trolley case is 38 cm * 60 cm * 28 cm. It can't be boarded and is suitable for a person to travel for 3-7 days.   It is now a very common trolley case. The volume is moderate, and there are many items that can be held. If you are a college student or a white-collar worker, this trolley case can basically meet your travel needs.   28 inch Trolley Case   The most common size design of 28 inch trolley case is 48 cm * 70 cm * 30 cm. It is already relatively large in the lineup of trolley cases. You can't board a plane. It's suitable for a person to travel for more than 7 days. It is suitable for business personnel or students. The 28 inch large capacity can put down enough living and working supplies, which may be used as a mobile small warehouse. It is worth mentioning that the trolley case with the sum of three sides less than 158CM is an international standard consignment case. If you want to go abroad, try to control it below 28 inches.   Material chapter   After making clear how big the trolley case we need, we will next look at the material of the trolley case. The material directly determines its applicability, and most trolley cases will clearly indicate their main materials when they are sold. If you can understand the different properties of different materials, it will also bring convenience to purchase. According to the material, trolley cases are usually divided into hard cases and soft cases. Most of the hard boxes have the characteristics of high temperature resistance, wear resistance, impact resistance, waterproof and compression resistance. The hard shell material can protect the contents from extrusion and impact. The disadvantage is that the internal capacity is relatively fixed; Soft boxes can bring users flexible use space, and most of them are light in weight and strong in toughness.   ABS material   The main material of the hard box is made of, and most of the pull rod boxes made by it are formed by thermal vacuum. The trolley case has a delicate interior and the surface of the case shell changes a lot, which is more impact resistant than the soft case, but the weight is relatively heavy due to the existence of the box frame. However, solid it can protect clothes from wrinkle and damage fragile goods. When using, try to fill it up, press it and then close it. ABS is basically a very durable material.   Details   Box body   Whether it is a hard case or a soft case, the case of the trolley case must be very neat. First, check whether the corners of the box are symmetrical and whether the surface of the box is flat.You can put the box upright or upside down on the ground and check whether the box is on four feet. At the same time, check whether there are scratches and cracks on the surface of the box. If it is a soft box, pay more attention to the stitching of textile fabrics. A good workmanship will not expose even a thread. The material on the surface of the box should be well sealed, rainproof and waterproof, and the particle size of the surface material should be larger, so that the surface is easier to wear. Of course, now there are many smooth surface materials, which are also more wear-resistant after special treatment. However, once a scratch is left, the smooth surface is much more obvious than the rough surface.   pull rod   The pull rod of the trolley case is generally built-in now, so the structural stability will be stronger. The external pull rod will be inconvenient when loading, and it is very easy to be damaged. It has basically been eliminated by the mainstream of the times. If possible, we should also open the inner lining to observe the color of the inner tube. If it is black, it may be an iron tube. Our choice tends to be steel. Only with such a tie rod can we withstand all kinds of pressure and hold all kinds of scenes. When testing the pull rod, be sure to test the locking button several times. After pressing it, it should be able to expand and contract freely, with a very smooth and unobstructed feeling. After the pull rod is extended, you should test the stability. Many airport and railway station building structures are full of stairs and steps, and there are high requirements for the operation balance of the pull rod up and down, which must be judged carefully. And it's useless for an adult to stand on the pull rod of our family!   Wheel   The wheel is the most consumed part on the trolley case, and the quality must be excellent. When you evaluate, you must pull more. The sound of a good wheel will be very small, the smaller the better. In addition to sound, the diameter of the wheel is also crucial. If your trolley has a large diameter wheel, it will certainly save you a lot of effort, and the large diameter wheel should stand the test of time wear and tear. It is worth mentioning that the wheels of the trolley box now often have directional wheels with two wheels or universal wheels with four wheels.