Carry-on baggage is stated on your ticket purchased with the airline as it's depending on the aircraft that the passenger is flying. Regardless of the aircraft you are flying, the items onboard must fit within the overhead lockers or under the seat in front.
Any passengers exceeding the carry-on limit may be charged with an excess fee or be asked to be transported as checked baggage. Oversized items must not be carried onboard for safety reasons.
Prohibited items cannot be carried onboard including any fluid exceeding 100ml. This includes items such as toothpaste, hair gel, shampoo, etc. Any fluid within 100ml must be placed in a plastic bag ready for airport security.