According to General Terms and Conditions for Passenger Baggage (Domestic) Transportation of China United Airlines Co., Ltd.:
Article 46? Non-checked baggage
(1) Each passenger can carry one piece of non-checked baggage free of charge, with the weight not exceeding 10kg and the volume not exceeding 20×30×40 cm. Unless the checked baggage exceeds this specification, but it does not exceed 20×40×55 cm and its weight does not exceed 10 kg, it can only be brought into the cabin after payment.
(2) Carry-on non-checked baggage exceeding the above weight, number of pieces or volume limit shall be checked as checked baggage.
(3) Lithium batteries can only be carried as non-checked baggage.
Because the size of the 20-inch barbell box is 34cm long, 50cm high and 20cm wide, it can be carried with you after payment.
Extended data:
China United Airlines Co., Ltd. Passenger and Luggage (Domestic) Transportation:
1.3.2? Paid checked baggage: baggage that cannot be brought into the cabin by plane and checked to the destination. The weight of each piece shall not exceed 50 kg, and the volume shall not exceed 40×60× 100 cm. Baggage exceeding the above standards can only be checked after on-site consultation by the staff.
1.3.3? When the baggage exceeding 10 kg or the volume exceeding 20×40×55 cm is intercepted at the boarding gate, the baggage will not arrive on the same plane, and will be checked by the next nearest flight to the destination airport, with standard charges.
1.3.4? Pay for carry-on baggage: Baggage with a volume of more than 20×30×40 cm but not more than 20×40×55 cm and a weight of less than 10kg can only be brought into the cabin of the plane after payment, and the charging standard is 200 yuan/piece.
References:
China United Airlines-China United Airlines Co., Ltd. Passenger and Freight (Domestic) Transportation General